Evolution 3e TE v5

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ISSUES AND Evolution
LIFE SCIENCE
TEACHER EDITION

THIRD EDITION

REDESIGNED FOR THE NGSS

THE LAWRENCE HALL OF SCIENCE
UNIVERSITY OF CALIFORNIA, BERKELEY

This book is part of SEPUP’s Issues and Science course sequence. For more
information about this sequence, see the SEPUP and Lab-Aids websites.

ISSUES AND EARTH SCIENCE

ISSUES AND LIFE SCIENCE

ISSUES AND PHYSICAL SCIENCE

Additional SEPUP instructional materials include:
SEPUP Modules: Grades 6–12
Science and Sustainability: Course for Grades 9–12
Science and Global Issues: Biology: Course for High School Biology

This material is based upon work supported by the National Science Foundation under
Grant 9554163 and 0099265. Any opinions, findings, and conclusions or recommenda tions
expressed in this material are those of the authors and do not necessarily reflect the views of
the NationalScience Foundation.

The preferred citation format for this book is SEPUP. (2017). Issues and Life Science: Evolution.
Lawrence Hall of Science, University of California at Berkeley. Published by
Lab-Aids®, Inc., Ronkonkoma, NY

Third Edition

Q5 6 7 8 9 22 21 20 19

© 2017 The Regents of the University of California

ISBN: 978-1-63093-468-2

v5

SEPUP
Lawrence Hall of Science
University of California at Berkeley
Berkeley CA 94720-5200

e-mail: [email protected]
Website: www.sepuplhs.org

Published by:

17 Colt Court
Ronkonkoma NY 11779
Website: www.lab-aids.com

ISSUES & LIFE SCIENCE THIRD EDITION
Director: Barbara Nagle
Co-Director: John Howarth
Coordinator: Janet Bellantoni

AUTHORS
Wendy Jackson,Tiffani Quan, Barbara Nagle, Manisha Hariani

OTHER CONTRIBUTORS
Asher Davison, Daniel Seaver

PRODUCTION
Coordination, Design, Photo Research: Seventeenth Street Studios
Layout and Composition: Kristine Rappa
Production Coordinator for Lab-Aids: Hethyr Tregerman
Editing: Kerry Ouellet

  iii

F IEL D TES T C E N T E R S 
The classroom is SEPUP’s laboratory for development.We are extremely appreciative of the
following center directors and teachers who taught the program during the 2003–04 and
2004–05 school years. These teachers and their students contributed s­ ignificantly to
improving the first edition of the course. Since then, Issues and Life ­Science has been used in
thousands of classrooms across the United States.This third edition is based on what we
have learned from teachers and students in those classrooms. It also includes new data and
information, so the issues included in the course remain fresh and up-to-date.

REGIONAL CENTER, SOUTHERN CALIFORNIA
Donna Markey, Center Director
Kim Blumeyer, Helen Copeland, Pat McLoughlin, Donna Markey,
Philip Poniktera, Samantha Swann, Miles Vandegrift

R EG ION AL CE N T E R , I OWA
Dr. Robert Yager and Jeanne Bancroft, Center Directors
Rebecca Andresen, Lore Baur, Dan Dvorak, Dan Hill, Mark Kluber, Amy Lauer,
Lisa Martin, Stephanie Phillips

REGIONAL CENTER, WESTERN NEW YORK
Dr. Robert Horvat, Center Director
Kathaleen Burke, Dick Duquin, Eleanor Falsone, Lillian Gondree, Jason Mayle,
James Morgan, Valerie Tundo

JEF F ER SO N C O U N T Y, K E N T U C K Y
Pamela Boykin, Center Director
Charlotte Brown, Tara Endris, Sharon Kremer, Karen Niemann,
Susan Stinebruner, Joan Thieman

LIVERMORE, CALIFORNIA
Scott Vernoy, Center Director
Rick Boster, Ann Ewing, Kathy Gabel, Sharon Schmidt, Denia Segrest,
Bruce Wolfe

QUEENS, NEW YORK
Pam Wasserman, Center Director
Gina Clemente, Cheryl Dodes, Karen Horowitz, Tricia Hutter, Jean Rogers,
Mark Schmucker, Christine Wilk

TUCSON, ARIZONA
Jonathan Becker, Center Director
Peggy Herron, Debbie Hobbs, Carol Newhouse, Nancy Webster

INDEPENDENT
Berkeley, California: Robyn McArdle
Fresno, California: Al Brofman
Orinda, California: Sue Boudreau, Janine Orr, Karen Snelson
Tucson, Arizona: Patricia Cadigan, Kevin Finegan

REVISION CENTERS
Chicago, Illinois: Bejaza Duskic, Francis Panion, Robert Troher
Elmhurst, Illinois: Kelly Biala

  iv

Contents

Evolution TEACHER EDITION

T E AC H I N G T H E U N I T 

1 investigation 10 i n v e s t i g at i o n 
The Full Course 3 Fossilized Footprints 137

2 m o d e l i n g  11 i n v e s t i g at i o n  149
Hiding in the Background 17 Family Histories

3 r o l e p l ay  12 i n v e s t i g at i o n 
A Meeting of Minds 31 A Whale of a Tale 161

4 m o d e l i n g  13 i n v e s t i g at i o n 
Battling Beaks 45 Embryology 179

5 m o d e l i n g  14 ta l k i n g i t ov e r
Mutations: Good or Bad? 59 The Sixth Extinction? 195

6 co m p u t e r s i m u l at i o n  15 reading 
Mutations and Evolution 83 Bacteria and Bugs:
Evolution of Resistance 211
7 v i e w a n d r e f l e c t 
Origins of Species 95 16 in ve st ig at io n 
Manipulating Genes 219
8 re adi ng 
History and Diversity of Life 109 17 projec t 
Evolution and Us 231
9 l a b o r ato ry 
Fossil Evidence 121

 v

N G S S A N D CO M M O N CO R E  T-1
T-7
NGSS Overview T-11
Anchoring Phenomena, Driving Questions, and Storyline T-16
NGSS Correlations
Common Core State Standards Correlations T-19
T-25
U N I T O V E R V I E W A N D M AT E R I A L S  T-26
T-26
Unit Overview
Materials Provided in Kit T-27
Materials Not Provided in Kit T-28
Materials and Solution Prep T-28

L I T E R AC Y  T-29
T-31
Literacy Strategies Embedded T-47
Opportunities for Eliciting and Addressing Students’ Ideas
Differentiation Opportunities

A S S E S S M E N T 

Assessment Blueprint
Item Bank and Answer Key
Item Bank Activity and NGSS Support

  vi

Evolution

TEACHER EDITION



1 The Full Course

i n v e s t i g at i o n
2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students use a model to explore the cause-and-effect relationship between
inappropriate use of antibiotics and the phenomenon of the evolution of antibiotic
resistance. As they use the model, students use mathematical representations to
support their analysis of patterns and trends in the results and to develop explanations
for how and why the population of bacteria is changing. These explanations are based
on the differential survival and reproduction of resistant bacteria when antibiotics are
present in their environment (the human body they are infecting).

Prepare to teach the unit by reviewing the Planning the Unit guide, found at the
front of this Teacher Edition or on your online Portal. This guide breaks down
the resources and equipment needed to teach the unit, explains how to develop
an understanding of the program design as a whole, and suggests to plan for
assessment and sensemaking before teaching the unit. Critical tools called out in
the guide include Unit Overviews, Assessment Blueprints, the NGSS 3D Pathways,
and the Phenomena, Driving Questions, and Storyline to summarize the NGSS
taught and assessed in each unit. Additionally, the Guide to Student Sensemaking,
Driving Question Board cards, and slide decks call attention to the students’
roles in the unit progression. If this is your first SEPUP unit, read through the
Teacher Resources I, II, and III, for more detailed information on the program.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-4: Construct an explanation based on evidence that
describes how genetic variations of traits in a population increase some individuals’
probability of surviving and reproducing in a specific environment.

Working towards MS-LS4-6: Use mathematical representations to support
explanations of how natural selection may lead to increases and decreases of
specific traits in populations over time.

EVOLUTION  3

ACTIVITY 1  THE FULL COURSE

Disciplinary Core Ideas
MS-LS4.B Natural Selection: Natural selection leads to the predominance of
certain traits in a population, and the suppression of others.
MS-LS4.C Adaptation: Adaptation by natural selection acting over generations
is one important process by which species change over time in response to
changes in environmental conditions. Traits that support successful survival and
reproduction in the new environment become more common; those that do not
become less common. Thus, the distribution of traits in a population changes.

Science and Engineering Practices
Analyzing and Interpreting Data: Analyze and interpret data to determine
similarities and differences in findings.
Developing and Using Models: Develop and use a model to predict and/or describe
phenomena.
Using Mathematics and Computational Thinking: Use mathematical representations
to describe and/or support scientific conclusions and design solutions.

Crosscutting Concepts
Patterns: Patterns can be used to identify cause and effect relationships.
Cause and Effect: Phenomena may have more than one cause, and some cause and
effect relationships in systems can only be described using probability.

Common Core State Standards—Mathematics
6.SP.B.5: Summarize numerical data sets in relation to their context.
6.RP.A.1: Understand the concept of a ratio, and use ratio language to describe a
ratio between two quantities.

Common Core State Standards—ELA/Literacy
RST.6-8.3: Follow precisely a multistep procedure when carrying out experiments,
taking measurements, or performing technical tasks.

WHAT STUDENTS DO
Students model the effects of antibiotics on a population of disease-causing
bacteria during an infection. Students toss number cubes to determine whether
an infected individual remembers to take the prescribed daily dose of antibiotics,
which in turn affects the size and antibiotic resistance of the bacterial population

4 EVOLUTION

THE FULL COURSE ACTIVITY 1

in the patient. Students keep track of and graph the population size of the
remaining bacteria depending on their resistance to antibiotics. Students consider
the effect of changing the chemical environment on the survival of bacteria with
varying levels of antibiotic resistance.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Scoring Guide: organizing data for analysis (oda)

■■ For each pair of students

1 set of 50 disks (20 green, 15 blue, 15 orange)
4 colored pencils (including green, blue, orange)
1 number cube

■■ For each student

1 Student Sheet 1.1, “Bacteria Graph”
1 Science Skills Student Sheet 4a and 4b, “Scatterplot and Line Graphing

Checklist” (optional)
1 Scoring Guide: organizing data for analysis (oda) (optional)

TEACHING SUMMARY

GET STARTED

1. Create personal student connections through a scenario of a sick person taking
antibiotics.
a. Ask students if they’ve ever taken an antibiotic when they’ve been sick.
b. Have students read the scenario and introduction.

DO THE ACTIVITY

2. (literacy) If you have not done so in previous units, introduce the use of a
science notebook.

Explain your expectations for the type and organization of students’
notebooks.

3. Student pairs use a model to simulate taking antibiotics as prescribed or not as
prescribed.
a. Introduce students to the model by reviewing the box titled, “A Bacterial
Infection.”
b. Direct students to the Procedure.

EVOLUTION  5

ACTIVITY 1  THE FULL COURSE

4. (oda quick check) Students graph the results of their simulations.

a. (mathematics) Distribute Student Sheet 1.1, “Bacteria Graph,” for
students to use in Procedure Step 7.

b. If you have not previously done so, introduce the SEPUP Assessment
System with Procedure Step 7.

c. Provide an overview of the Scoring Guides.

d. Explain the expectations for student growth over time.

BUILD UNDERSTANDING

5. Students share their graphs for class discussion.

a. Ask two or three pairs to share and explain their graphs.

b. Instruct students to answer Analysis item 1 individually in their science
notebooks.

6. As a class, students discuss Analysis item 2.

a. Direct students to Analysis item 2 about providing an explanation for
their findings.

b. Bring the class together, and have the groups you’ve identified share their
explanations.

c. Ask some questions to get students thinking about evolution and cause
and effect.

TEACHING STEPS

GET STARTED

1. Create personal student connections through a scenario of a sick person taking
antibiotics.

a. Ask students if they’ve ever taken an antibiotic when they’ve been sick.

Follow this question by asking them if they can remember any specific
instructions they received from their doctors about taking the antibiotic.
Elicit their ideas about the reasons for these instructions and whether they
have always complied.

This is a good place to reintroduce the first driving question for this
sequence of learning. Revisit and add to or revise students' ideas as needed.

b. Have students read the scenario and introduction. 123

Emphasize that doctors always instruct their patients to finish the full
course of antibiotics, and in this activity, students will use a model to

1 NGSPDM1
2 NGLS4B1
3 NGLS4C1

6 EVOLUTION

THE FULL COURSE ACTIVITY 1

understand why this instruction is important. Emphasize that antibiotics
are chemical substances that kill or inhibit the growth and reproduction of
bacteria and other kinds of infectious agents, with the exception of viruses.

DO THE ACTIVITY

2. (literacy) If you have not done so in previous units, introduce the use of a
science notebook.4

Explain your expectations for the type and organization of students’
notebooks.

Keeping a science notebook helps students to track data; record predictions,
hypotheses, and questions as they investigate; process ideas; build scientific
writing skills; and write lab reports. Keeping a Science Notebook in Appendix
E of the Student Book provides suggested guidelines. For more information
about science notebooks, see the Literacy section of Teacher Resources II,
“Diverse Learners.”

3. Student pairs use a model to simulate taking antibiotics as prescribed or not as
prescribed.

a. Introduce students to the model by reviewing the box titled, “A Bacterial
Infection.”

In this model, bacteria are represented by plastic disks. The relative
resistance to antibiotics is indicated by the color of the disk. Whether
or not a person remembers to take the antibiotic on a given day is
represented by the number on the cube.

b. Direct students to the Procedure.5

Consider bringing the whole class together after one round to ensure
that they understand the model. Provide support for students as they
implement Procedure Steps 1–6.

4. (oda quick check) Students graph the results of their simulations.

a. (mathematics) Distribute Student Sheet 1.1, “Bacteria Graph,” for
students to use in Procedure Step 7.

4 SELTSN1 Point out to students Appendix C, “Scatterplot and Line Graphing
5 ELRS683 Checklist,” in their Student Books, and review with your class as
6 SESSLG1 necessary.You might also consider making copies of this same checklist,
7 MARP6A1 available as Student Skill Sheets 4a and 4b. While the Next Generation
8 MASP6B5 Science Standards (NGSS) expect students to be proficient at making
this kind of graph by the end of fifth grade, some students may need
reminding or the additional scaffolding provided on this Skill Sheet.678

EVOLUTION  7

ACTIVITY 1  THE FULL COURSE

This Student Sheet has the axes drawn with tick marks and lines where the
title, key, and axes labels should go. For students who need more scaffolding,
consider filling in any or all of these blank lines before making copies.

b. If you have not previously done so, introduce the SEPUP Assessment
System with Procedure Step 7.

Explain that the graph assigned in Procedure Step 7 is the first assessment
in this unit. Explain that you will use it as an example to introduce the
SEPUP Assessment System to your students. See Teacher Resources III,
“Assessment,” to be sure you are familiar with the overall system.

c. Provide an overview of the Scoring Guides.

Before assigning the assessment, distribute the organizing data for
analysis (oda) Scoring Guide, and use it to model how the system works.
Point out the levels in the first column of the Scoring Guide. Tell students
that these levels are the same for all Scoring Guides and range from
0 to 4. Then review the descriptions of each level. For example, a Level-4
response is complete and correct in all Scoring Guides. Point out that
the scores (0–4) are based on the quality of student responses and do
not correspond to letter grades. Allow students to refer to the Scoring
Guide as they prepare their answers. Be sure that they understand that
the Scoring Guides do not include the specific content students must
provide in their responses; rather, they explain the overall expectations
for responses at various levels of performance on the task. For more
information about the Scoring Guides and how you and students
can use the system to improve their work, see Teacher Resources III,
“Assessment.” 9

d. Explain the expectations for student growth over time.

Explain to students that they aren’t expected to always produce complete
and correct work on their first attempts. Instead, they should work toward
developing consistent Level-3 and Level-4 answers as they become more
proficient with the concepts (both disciplinary core ideas and crosscutting
concepts) and science and engineering practices being assessed. It is not
necessary (or even expected) that an “A” student will always write Level-4
responses, especially at the beginning of the course or when they are
introduced to a new Scoring Guide. For a sample Level-4 response, see
Sample Student Response to Student Sheet 1.1 at the end of this activity.

Let students know that they will not be formally assessed on their graphs at
this time. Rather, this item is a Quick Check, which is an opportunity for
you to gauge students’ abilities to organize data for analysis. See Teacher
Resources III, “Assessment,” for more information on Quick Checks.

9 SEASOD1

8 EVOLUTION

THE FULL COURSE ACTIVITY 1

BUILD UNDERSTANDING

5. Students share their graphs for class discussion.

a. Ask two or three pairs to share and explain their graphs.10

Select pairs whose graphs show different results depending on when and
how often they skipped a dose of antibiotics.

b. Instruct students to answer Analysis item 1 individually in their science
notebooks.

Check that students are able to answer this straightforward question
and that they are using their notebooks to record their ideas. They can
reference the graphs on the Student Sheet.

6. As a class, students discuss Analysis item 2.

a. Direct students to Analysis item 2 about providing an explanation for
their findings.

Allow students time to discuss this question in their groups first.
Circulate throughout the room and identify two or three groups to share
their explanations. Look for groups who have different yet plausible
explanations to generate a productive class discussion.

b. Bring the class together, and have the groups you’ve identified share their
explanations.

This question serves to set the stage for the next several activities. Thus,
do not expect all students to have a well-thought-out explanation at this
point.

c. Ask some questions to get students thinking about evolution and cause
and effect.11

Dr. Torres said the bacteria are evolving; what did the doctor mean
by that? This question will elicit some initial student thinking about
evolution.

What if the initial population had included only sensitive bacteria? What
if the antibiotic had not been introduced? How would things differ? These
questions emphasize cause and effect. The crosscutting concept of cause
and effect will be introduced formally in the next activity; introducing the
term here will help them begin to understand this kind of relationship.
For example, having only sensitive bacteria present when beginning to
take an antibiotic will cause all of those bacteria to be eliminated.

10 NGCCPA1
11 NGCCCE2

EVOLUTION  9

ACTIVITY 1  THE FULL COURSE

These icons, , indicate where you can formatively assess student proficiency

of the 3 dimensions: = SEP, = DCI, = CCC.

SAMPLE RESPONSES TO ANALYSIS

1. Describe what happened when you or a classmate

a. remembered to take the antibiotic according to the instructions.

When I remembered to take the antibiotic, the bacteria were eliminated
completely by the time the medicine was finished. None of the bacteria were able
to increase to high levels.

b. missed several doses of the antibiotic. 12131415

When I forgot to take the antibiotic, the bacteria were able to remain, especially
the bacteria that are highly resistant to the antibiotic. Even though the least
resistant bacteria were killed off, the highly resistant bacteria were able to
increase in number and remain in the body.

2. Provide an explanation for these results.16

Hint: How do bacteria differ, and what is happening to the bacteria when they
are exposed to antibiotics in their environment?

Student responses may vary. One sample response is shown here:

Antibiotics help your body fight off an infection by killing or reducing the bacteria. A
small number of bacteria in any population in your body may not be affected by the
antibiotic as quickly.These bacteria have something that makes them more resistant
to the antibiotic, and they continue to reproduce and grow. Completing the full course
of the antibiotic as prescribed helps make sure that these bacteria do not survive and,
therefore, won’t make you ill or infect anyone else.

3. Reflection: Have you or any of your family members ever taken an antibiotic?
If so, did you follow instructions? How has this activity affected the way you
will take antibiotics in the future?

Student responses may vary. One sample response is shown here:

We have taken antibiotics, and we usually follow the instructions. But once when I
felt better after only 2 days I stopped taking the medicine. From now on, I’ll know
why I should finish it all.

12 MARP6A1
13 MASP6B5
14 NGSPAD1
15 NGCCPA1
16 NGCCCE2

10 EVOLUTION

THE FULL COURSE ACTIVITY 1

REVISIT THE GUIDING QUESTION

What happens when a person does not take antibiotics as prescribed?

When a person doesn’t take antibiotics as prescribed, any bacteria that are more
resistant to the antibiotic can stay alive and reproduce. Eventually, the highly
resistant bacteria may become the most common in the body, and the person can
remain sick. The bacteria they pass on to other people are more likely to be the
resistant type. 1718

This is a good place to reintroduce the second and last driving questions for this
sequence of learning. Revisit and add to or revise students' ideas as needed.

ACTIVITY RESOURCES

KEY VOCABULARY

antibiotic

BACKGROUND INFORMATION

BACTERIAL RESISTANCE

Bacteria, both beneficial and harmful, live within the human body. Infections
occur when the size of a population of harmful bacteria (either indigenous or
introduced) grows too large. Antibiotics have been extremely successful in fighting
bacterial infections since their discovery in the 1930s. The antibiotic used depends
on the microbe causing an infection. Today, many antibiotics are less effective
because resistant bacterial strains have become more prevalent. They have evolved
due to natural selection in an environment that includes antibiotics. This can
occur when some bacteria in the population have genetic variations that naturally
confer some resistance to these medicines. It takes only a small number of resistant
microbes within a population to lead to an increase in resistant microbes. As
the rest of the bacterial population is killed off, the resistant bacteria face no
competition and can reproduce more successfully. As a result, increased use of
antibiotics can lead to the development (evolution) of resistant strains.

The possibility that disease-causing organisms could become resistant to treatment
with antibiotics was first observed in 1943, when penicillin was being developed
for use. It was during the second clinical trial of penicillin that one of the 15
patients died from a strep infection because the microbe had become resistant
to the antibiotic. Today, there are antibiotic-resistant strains of many different
disease-causing microbes, including Streptococcus pneumoniae (which causes ear
infections and meningitis), Mycobacterium tuberculosis (which causes tuberculosis),

17 NGLS4B1
18 NGLS4C1

EVOLUTION  11

ACTIVITY 1  THE FULL COURSE

Haemophilus influenzae (which causes respiratory infections), and Neisseria
gonorrhoeae (which causes gonorrhea). More than 90 strains of Staphylococcus
aureus bacteria, a common cause of hospital staph infections, are now resistant to
penicillin. Some microbes, including those that cause staph and tuberculosis, have
evolved multi-drug resistance, increasing concerns about our ability to fight these
infections as these strains spread.
This is one reason it is important to reduce the unnecessary use of antibiotics and
other antibacterial agents. Overprescribing and misuse contribute to the problem,
and many health care providers are more carefully monitoring their patients’ use
of antibiotics. Some researchers are also recommending that the routine use of
antibacterial soaps and other such products be reduced.
Patients have played, and continue to play, an important role in the developing
crisis. Many people who have been given prescriptions start feeling better after a
few days and stop taking the antibiotic. All of the microbes may not yet have been
killed, especially those with more antibiotic resistance. These still-living resistant
bacteria then reproduce. This increases their population and increases the chance
of their causing future infections that cannot be treated with a typical course of
antibiotics. However, this crisis is not due to patients alone. Health care policies
have also contributed. In some countries, many antibiotics are available without a
prescription, and thus the opportunity for misuse in these areas is even greater. In
some cases, doctors have prescribed antibiotics unnecessarily, either as a placebo
or because patients demand them. As more and more antibiotics are prescribed,
the non-resistant strains are killed, allowing the population size of the resistant
strains to increase, especially as they are passed from individual to individual.

12 EVOLUTION

©2017 The Regents of the University of California Name______________________________________________________________ Date____________

STUDENT SHEET 1.1

BACTERIA GRAPHS

Key
=
=
=
=

LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 1_1 StudentSheet
MyriadPro Reg 9.5/11

Name_______S_a__m__p__le__s__tu__d_e__n_t__r_e_s_p__o_n__s_e__1_________________________ Date____________

STUDENT SHEET 1.1

BACTERIA GRAPHS

20

Key
Least resistant bacteria
Resistant bacteria
Extremely resistant bacteria
15 Total number of bacteria

Number of Bacteria 10

5

0
1 23 4 5 6 7 8
Time (in days)

©2017 The Regents of the University of California Toss number Least resistant Resistant bacteria Extremely resistant Total
bacteria bacteria
Initial 6 2 20 0
1 13 7 1 18
2 9 8 2 16
3 5 9 3 13
4 0 5 4 10
5 0 0 5 6
6 0 0 6 2
7 0 0 2 0
8 0 0

Name_______S_a__m__p__le__s__tu__d_e__n_t__r_e_s_p__o_n__s_e__2_________________________ Date____________

STUDENT SHEET 1.1

BACTERIA GRAPHS

Key
Least resistant bacteria
20 Resistant bacteria

Extremely resistant bacteria
Total number of bacteria

15

Number of Bacteria 10

5

0
1 23 4 5 6 7 8
Time (in days)

©2017 The Regents of the University of California Toss number Least resistant Resistant bacteria Extremely resistant Total
bacteria bacteria
Initial 6 2 20 0
1 13 7 1 18
2 9 8 2 16
5 9 3 19
3 (forgot) 6 10 4 17
4 2 8 5 14
5 0 9 6 16
0 5 7 13
6 (forgot) 0 0 8 9
7 0 9
8



2 Hiding in the Background

modeling
2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students use a model to explain how a change in the environment—a change
in predation—can cause changes in trait frequency within a population of
prey. Students analyze and interpret data from their model using mathematical
representations in their explanations.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-4: Construct an explanation based on evidence that
describes how genetic variations of traits in a population increase some individuals’
probability of surviving and reproducing in a specific environment.

Working towards MS-LS4-6: Use mathematical representations to support
explanations of how natural selection may lead to increases and decreases of
specific traits in populations over time.

Disciplinary Core Ideas

MS-LS4.B Natural Selection: Natural selection leads to the predominance of
certain traits in a population, and the suppression of others.

MS-LS4.C Adaptation: Adaptation by natural selection acting over generations
is one important process by which species change over time in response to
changes in environmental conditions. Traits that support successful survival and
reproduction in the new environment become more common; those that do not
become less common. Thus, the distribution of traits in a population changes.

MS-LS2.A Interdependent Relationships in Ecosystems: In any ecosystem, organ-
isms and populations with similar requirements for food, water, oxygen, or other
resources may compete with each other for limited resources, access to which
consequently constrains their growth and reproduction.

EVOLUTION  17

ACTIVITY 2  HIDING IN THE BACKGROUND

Science and Engineering Practices
Analyzing and Interpreting Data: Analyze and interpret data to determine
similarities and differences in findings.
Developing and Using Models: Develop and use a model to predict and/or describe
phenomena.
Constructing Explanations and Designing Solutions: Construct an explanation that
includes qualitative or quantitative relationships between variables that predict or
describe phenomena.
Using Mathematics and Computational Thinking: Use mathematical representations
to describe and/or support scientific conclusions and design solutions.

Crosscutting Concepts
Cause and Effect: Phenomena may have more than one cause, and some cause and
effect relationships in systems can only be described using probability.
Patterns: Patterns can be used to identify cause and effect relationships.

Common Core State Standards—Mathematics
6.SP.B.5: Summarize numerical data sets in relation to their context.
6.RP.A.1: Understand the concept of a ratio, and use ratio language to describe a
ratio between two quantities.

Common Core State Standards—ELA/Literacy
RST.6-8.3: Follow precisely a multistep procedure when carrying out experiments,
taking measurements, or performing technical tasks.

WHAT STUDENTS DO
Using toothpicks of two colors, students simulate the effect of prey coloration
on predation rates by birds. They calculate and graph the changing frequencies
of worm colors over successive generations. Students consider how this model is
similar to the antibiotic scenario in the previous activity.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Scoring Guide: organizing data for analysis (oda)
1 Scoring Guide: analyzing and interpreting data (aid)
1 Visual Aid 2.1, “Worm Color Model”
* green or beige paper, cloths, or rugs (optional)

18 EVOLUTION

HIDING IN THE BACKGROUND ACTIVITY 2

■■ For each group of four students

2 paper bags
50 green toothpicks
50 beige toothpicks

■■ For each student

1 clear plastic sandwich bag
1 Student Sheet 2.1, “Worm Populations”
* 1 piece of graph paper
1 Scoring Guide: organizing data for analysis (oda) (optional)
1 Scoring Guide: analyzing and interpreting data (aid) (optional)

* not included in kit

The “toothpicks” provided in the equipment kit are thin green and beige
plastic rods. The activity requires 50 toothpicks of each color for each group of
four students. Extras are provided to replace any that may become lost during
the activity. Alternatives include dyed and undyed pasta. This activity is best
conducted outdoors on green grass. The color and texture of healthy grass usually
makes the green toothpicks slightly more difficult to see, providing more predict-
able results. However, this activity can also be conducted on concrete (preferably
beige in color, similar to that of the beige toothpicks) or indoors in the classroom.
If this activity is conducted in the classroom, you may wish to use either green or
beige paper, cloths, or rugs to cover sections of the floor.

TEACHING SUMMARY

GET STARTED

1. Students are introduced to the Toothpick Worm Model.
a. Introduce the scenario involving worms and birds that eat the worms.
b. Ask students, “Which worms do you think are more likely to be eaten?”
c. Ask students, “What do you think would happen to the color of the worm
population over many generations, and why?”
d. Inform the class that they will be testing their predictions with a
population of green and beige “worms.”

DO THE ACTIVITY

2. If you have not previously done so, introduce the SEPUP model for
collaborative work.
a. Introduce SEPUP’s 4–2–1 model for collaborative work.

EVOLUTION  19

ACTIVITY 2  HIDING IN THE BACKGROUND

b. Clarify which situations are appropriate for collaboration and which are
appropriate for working independently.

c. Introduce strategies for effective group interaction, and introduce the
strategy “Developing Communication Skills,” found in Appendix E in the
Student Book.

3. Students groups model how toothpick-worm color affects the rate of survival.

a. Direct students to Procedure Steps 1–6, and model how to distribute and
pick up the toothpicks.

b. (mathematics) Distribute Student Sheet 2.1, “Worm Populations,” and
model how to fill in the tables.

c. Instruct students to perform the simulation for Generation 1.

d. When students have completed the first generation, consider bringing the
class together to discuss Generation 2.

e. (oda assessment) Instruct students to continue the simulation through
Generation 3, and then graph their results in Procedure Step 12.

TEACHING STEPS

GET STARTED

1. Students are introduced to the Toothpick Worm Model.19

a. Introduce the scenario involving worms and birds that eat the worms.

Ask students to imagine a population of worms in which there is some
variation in color: some worms are lighter and some are darker. Birds eat
these worms. Most of the birds that eat these worms are better at seeing
lighter worms.

b. Ask students, “Which worms do you think are more likely to be eaten?”

Students are likely to predict the lighter worms because they are easier to
find. Clarify that this means that the lighter worms have a lower chance of
surviving; scientists use the term probability of surviving.

c. Ask students, “What do you think would happen to the color of the worm
population over many generations, and why?”

Students are likely to state that the worm population would become
darker over time. Accept all reasonable explanations at this point for why
this might happen. At the end of this activity, students should be able
to explain that the frequency of the worms that are more difficult to see
will increase in the population due to their greater ability to survive and
reproduce. 202122

19 NGSPDM1
20 NGLS2A2
21 NGLS4B1

2220  EVOLUNGTLIS4OC1N

HIDING IN THE BACKGROUND ACTIVITY 2

d. Inform the class that they will be testing their predictions with a popula-
tion of green and beige “worms.”
Point out that the green and beige toothpicks will represent the worms,
and that students, themselves, will be the “birds.”
Be sensitive to the fact that up to 8% of males are red-green colorblind
and may not be able to distinguish the green and beige toothpicks very
easily (although they may be capable of this due to differences in intensity
of color). However, this is unlikely to have a major effect on the results of
the simulation, since it is performed by groups of four students.

DO THE ACTIVITY
2. If you have not previously done so, introduce the SEPUP model for collabora-

tive work.
a. Introduce SEPUP’s 4–2–1 model for collaborative work.

Explain that many of the activities in this book use the SEPUP 4–2–1
cooperative learning model. Students work in groups of four or in
pairs to share, discuss, compare, and revise their ideas and to conduct
investigations and activities. In all cases, each individual student is
responsible for contributing ideas, listening to others, recording and
analyzing their results, and monitoring their own learning.
b. Clarify which situations are appropriate for collaboration and which are
appropriate for working independently.
In science, collaboration is essential to the development of new ideas and
to a better understanding of scientific concepts. However, scientists must
publish only their own work and must give others credit when they build
on others’ ideas.
c. Introduce strategies for effective group interaction, and introduce the
strategy “Developing Communication Skills,” found in Appendix E in the
Student Book.
Explain or model what productive group interactions and communication
(both agreement and constructive disagreement) look like and sound
like. For more information about group work, including optional Student
Sheets to help support students’ interactions, see the Facilitating Group
Interactions section of Teacher Resources II, “Diverse Learners.”23

23 SESSGI2

EVOLUTION  21

ACTIVITY 2  HIDING IN THE BACKGROUND

3. Students groups model how toothpick-worm color affects the rate of survival.

a. Direct students to Procedure Steps 1–6, and model how to distribute and
pick up the toothpicks.

After scattering 25 beige and 25 green toothpicks on the ground, students
should pick up a toothpick as soon as they see it and place it in their
plastic bag. If students are working in groups of four, each of the four
picks up the first 10 toothpicks they see. If there are fewer than four
people in a group, they need to figure out how many toothpicks each
person will pick up to equal 40.

b. (mathematics) Distribute Student Sheet 2.1, “Worm Populations,” and
model how to fill in the tables.24

Generation 1 begins with 25 beige and 25 green worms; this has been
pre-filled in Row 1 of both tables. In Row 2, students record the number
of worms that survived predation.You may wish to model this in the first
table with, for instance, 7 surviving green worms.

To represent reproduction, students multiply this number by 4—this
represents each surviving adult worm having 4 offspring identical in color.
(If your students have had the Reproduction unit, you can explain that the
worms reproduce asexually.) Emphasize that green worms can produce
only green worms, and beige worms can produce only beige worms. In
this example, the 7 surviving green adults have 28 green offspring. This
number goes in Row 3. To determine the total number of worms at the
end of Generation 1, students add Rows 2 and 3. In this example,
7 + 28 = 35. This number is entered into Row 4.

c. Instruct students to perform the simulation for Generation 1.

Circulate among the groups to offer guidance where needed.

Note that it is possible for students to collect all of the toothpicks of a
particular color, reducing their population to zero and eliminating color
variation from the population. If this occurs, no additional toothpicks
of that color would be added to the population, and the next generation
would be a column of zeros.

d. When students have completed the first generation, consider bringing the
class together to discuss Generation 2.

To begin Generation 2, students begin with the number of green and
beige worms remaining at the end of Generation 1 (i.e., the numbers from
Row 4). These numbers are used in Row 1 of Generation 2.

24 NGSPUM1

22 EVOLUTION

HIDING IN THE BACKGROUND ACTIVITY 2

e. (oda assessment) Instruct students to continue the simulation for three
subsequent generations, and then graph their results in Procedure Step 12.25

In the previous activity, students were given a Student Sheet for making
the graphs. Here they are expected to make their own graphs using graph
paper. Students may reference their graphs from the last activity when
creating their graphs for this activity. Students may want to use different
colored pencils to represent the two worm colors, or they could use
different symbols. For a sample Level-4 response, see Sample Student
Response to Student Sheet 2.1 at the end of this activity, and Sample
Student Response, “Worm Population Graph,” below.

SAMPLE LEVEL-4 RESPONSENumber of worms at start of generation45

50 40

40
35

30 15 green worms
25 beige worms

20 10
5
10

01 2 3 4
Generation

BUILD UNDERSTANDING

4. If youLhaabvAeidns SoEtPdUoPnIAePsSoEvionluptiroenv3ioeus units, introduce the crosscutting concepts
of pattFMeigyrurnirased,:PEarvnoodR3eecgTaE9u.25s_/e111and effect.
a. Explain that crosscutting concepts bridge disciplines.

They can be a lens or touchstone through which students make sense of
phenomena and deepen their understanding of disciplinary core ideas.
Refer students to Appendix G, “Crosscutting Concepts,” and point out
the symbols and discuss definitions provided.

b. Introduce the crosscutting concept of patterns.26

Display the definition and symbol used for Patterns in Appendix G,
“Crosscutting Concepts.” The pattern can be structural, as shown in
the diagram, or a pattern in events, such as the pattern of results in

25 SEASOD1
26 NGCCPA1

EVOLUTION  23

ACTIVITY 2  HIDING IN THE BACKGROUND

which worm color is more likely to survive. Point out to students that
seeing patterns in nature can lead scientists to organize and classify their
observations. It can also lead them to ask questions about relationships
and the causes of patterns. Students will look for patterns when they
analyze and interpret data, ask questions about the patterns they observe,
and suggest cause-and-effect relationships to explain patterns.

c. Introduce the crosscutting concept of cause and effect: mechanism and
explanation.27

Scientists investigate and try to explain how things work, and try to
figure out what causes various events, including patterns, in their data.
Introduce the symbol for Cause and Effect in Appendix G, “Crosscutting
Concepts,” which shows a simple diagram of cause and effect, where
A (the cause) might or might not cause B (the effect) to happen. For
example, in this activity, beige worms in a green environment cause the
worms to be more visible to predators. The beige color is the cause, and
the increased visibility to predators is the effect.

5. The class discusses the results. 282930

a. Select two or three student groups to briefly summarize their results to
the class.

In most cases, groups will have similar results. If the activity was
conducted on green grass, for example, most groups are likely to see an
increase in the green worm population and a decrease in the beige worm
population.

b. Review the fact that worm color is a genetic characteristic by asking
students, “What if a beige worm were dyed green and released again into
the environment—would its chances of survival improve? What about its
offspring: would their chances of survival improve?”

c. Project Visual Aid 2.1, “Worm Color Model,” and have students explain
the model. 31

This model shows that against a beige surface, beige worms survive
because they are not eaten by a predator. They reproduce, and their
offspring are beige. Those beige offspring survive. If a green worm is
dyed or painted beige, this worm would survive because it likewise
escapes predation. However, its offspring are green. Their offspring have
little chance of survival because they are visible to predators, and the
green trait would die out eventually.

27 NGCCCE2
28 NGCCPA1
29 MARP6A1
30 MASP6B5
31 NGSPDM1

24 EVOLUTION

HIDING IN THE BACKGROUND ACTIVITY 2

d. (aid assessment) Direct students to answer Analysis item 1.32

Analysis item 1 is the first use of the analyzing and interpreting data
(aid) Scoring Guide. Optionally project or distribute the Scoring Guide.
Point out how it has the same levels like the previous guide but different
descriptions for each level. Review the levels as needed. For more
information, see Teacher Resources III, “Assessment.”

e. Have students complete the remaining Analysis items.

Note that Analysis item 3 assumes that the activity was conducted on
a green surface, resulting in increased survival of green worms. If this
was not the case in your classroom, consider rewriting the question to
reflect this. Use this question to emphasize the fact that natural selection
depends on the particular conditions in the environment.

SAMPLE RESPONSES TO ANALYSIS
1. (aid assessment) Look at your results. 3334353637

32 SEASAD1 SAMPLE LEVEL-4 RESPONSES
33 NGCCPA1
34 NGSPUM1 a. Compare the number of green worms to the number of beige worms
35 SEASAD1 using a ratio. For example, the ratio of green to beige worms in
36 MARP6A1 Generation 1 is 25:25, or 1:1.
37 MASP6B5
Sample ratios based on the sample data tables are shown here:
Generation 1: 25:25, or 1:1
Generation 2: 35:15, or about 2.3:1
Generation 3: 45:5, or 9:1

b. Calculate the percentage of green worms and beige worms in each
generation.
Generation 1: Green worms 50%, beige worms 50%
Generation 2: Green worms 70%, beige worms 30%
Generation 3: Green worms 90%, beige worms 10%

c. Describe how the percentage of green and beige worms changed over the
three generations.

The percentages are likely to have either increased or decreased,
depending on the surface on which the activity was conducted. In the case
of the sample data:

The percentage of green worms in the population increased significantly from the
first generation to the last. Beige worms, which were equal in percentage at the
start, declined to a very small percentage by the end.

EVOLUTION  25

ACTIVITY 2  HIDING IN THE BACKGROUND

d. Did any individual worm change color? Explain.

No, none of them changed color. Either the worm was eaten or the worm stayed
the same color and produced offspring of that color. No worm could change its
own color to blend into the environment.

e. Why do you think you observed this pattern?

Hint: A pattern is something that happens in a repeated and predictable
way. Provide a cause-and-effect explanation for this pattern.

The green toothpicks were harder to see in the grass.This allowed more green
worms to survive and reproduce, increasing their population while the overall
population of worms stayed constant.The opposite was true for the beige worms:
they were easier to see, which left fewer beige worms alive. Since fewer beige worms
were left, they could not have as many offspring, so their population went down.

2. Imagine that you performed this simulation for another generation. What do
you predict the percentage would be of green and beige in the population of
worms? Explain your prediction.

If their results show a trend, students may predict that the trend would
continue. For this example:

I predict that the beige worms will completely disappear from the population
eventually.This would cause the proportion of green worms to be 1.00 from then on. 38

3. Due to a drought, grass begins to dry out and die, leaving only dead grass stalks.
What is likely to happen to the percentage of green and beige worms? Explain. 252627

Dead grass stalks are beige.The beige worms would be harder to see than the green
worms.The beige worms would be more likely to survive and reproduce, while the
green worms would more likely be eaten.This means that not as many green worms
would survive to reproduce.This would make the ratio of green to beige worms
decrease, with the number of green worms going down and the number of beige worms
going up. (This can happen only if there are beige worms in the population when the
environmental change occurs.)

4. Compare and contrast your findings with those from the previous activity,
“The Full Course.” How are they similar? How are they different?

Both of the activities showed that when the environment changes, the populations
of organisms living in the environment change.The difference is that in “The Full
Course,” the environment was inside another organism, and an added chemical
substance changed the environment. In this activity, the change in the environment
was caused by a predator that hunted by seeing the worms.

38 NGSPDM1

26 EVOLUTION

HIDING IN THE BACKGROUND ACTIVITY 2

REVISIT THE GUIDING QUESTION

How does the environment affect an individual’s probability of survival and
successful reproduction?

As the environment changes, the trait that increases the chance of survival may
change. For example, in this activity, if the worms live in an environment that
is leafy and green, then a green individual has a trait that allows it to escape
predation, so it is more likely to survive and reproduce. That trait will then become
relatively more common in the next generation. But if the environment changes to
dirt or dry grass, the green trait may no longer increase the chance of survival, and
over time it is likely to become less common.

ACTIVITY RESOURCES

KEY VOCABULARY

pattern

trait

variation

BACKGROUND INFORMATION

ADAPTIVE COLORATION

Cryptic appearance is an adaptive characteristic found in countless animal species.
Color, texture, pattern, shape, or a combination of these characteristics can allow
an organism to blend in with its surroundings. The phenomenon is not limited
to prey species—for example, the stripes and spots of many of the big cats also
provide camouflage.

A classic example is that of the peppered moths in the Manchester area of
England. The first record of a black individual of this species was made in 1848;
by 1895, 98% of the population in that region was dark. In 1937, this dramatic
population shift was attributed to the effects of rapid industrialization, which
caused the tree trunks upon which the moths rested to darken with soot. In the
1950s, H. B. D. Kettlewell tested this hypothesis through the controlled release
and recapture of tagged moths, both dark and light, and both in areas with
soot-blackened trees and those untouched by the effects of factories. Recapture
statistics, along with videotaped footage of birds predating upon individual moths,
confirmed the hypothesis. The dark-colored trait, however, was not a direct effect
of the environmental change; it existed in the population before industrialization’s
effects as the result of random genetic mutations.

EVOLUTION  27

Name______________________________________________________________ Date____________

STUDENT SHEET 2.1

WORM POPULATIONS

Generation 1

1 Initial population Green worms Beige worms

25 25

2 Surviving adults

3 Offspring produced by surviving adults (multiply Row 2
by four [4] because each adult has four offspring)

4 Total number of survivors and offspring (add Row 2
and Row 3)

Generation 2

Green worms Beige worms

1 Initial population (from Row 4 in Generation 1)

2 Surviving adults

3 Offspring produced by survivors adults (multiply Row 2
by four [4] because each adult has four offspring)

4 Total number of surviving and offspring (add Row 2
and Row 3)

Generation 3

Green worms Beige worms

1 Initial population (from Row 4 in Generation 2)

2 Surviving adults

3 Offspring produced by surviving adults (multiply Row 2
by four [4] because each adult has four offspring)

4 Total number of survivors and offspring (add Row 2
and Row 3)
©2017 The Regents of the University of California

Name_______S_a__m__p__le__s__tu__d_e__n_t__r_e_s_p__o_n__s_e___________________________ Date____________

STUDENT SHEET 2.1

WORM POPULATIONS

Generation 1

1 Initial population Green worms Beige worms

2 Surviving adults 25 25
7 3
3 Offspring produced by surviving adults (multiply Row 2 28 12
by four [4] because each adult has four offspring)
35 15
4 Total number of survivors and offspring (add Row 2
and Row 3)

Generation 2

1 Initial population (from Row 4 in Generation 1) Green worms Beige worms

2 Surviving adults 35 15
8 2
3 Offspring produced by survivors adults (multiply Row 2 32 8
by four [4] because each adult has four offspring)
40 10
4 Total number of surviving and offspring (add Row 2
and Row 3)

Generation 3

1 Initial population (from Row 4 in Generation 2) Green worms Beige worms

2 Surviving adults 40 10
9 1
3 Offspring produced by surviving adults (multiply Row 2 36 4
by four [4] because each adult has four offspring)
45 5
4 Total number of survivors and offspring (add Row 2
and Row 3)
©2017 The Regents of the University of California

VISUAL AID 2.1

WORM COLOR MODEL

survives and
reproduces for
many generations

©2017 The Regents of the University of California dies survives and
painted reproduces
brown next generation
dies
LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 2_2 VisualAid
MyriadPro Reg 9.5/11

3 A Meeting of Minds

r o l e p l ay
1–2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students develop an understanding of Darwin’s Theory of Natural Selection and
use it to explain why species change over time. They learn why this explanation
has prevailed by listening to arguments supporting Darwin vs. Lamarck. They use
the theory to explain how a change in the environment causes a change in trait
frequency from one generation to the next.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-4: Construct an explanation based on evidence that
describes how genetic variations of traits in a population increase some individuals’
probability of surviving and reproducing in a specific environment.

Working towards MS-LS4-6: Use mathematical representations to support
explanations of how natural selection may lead to increases and decreases of
specific traits in populations over time.

Working towards MS-LS3-1: Develop and use a model to describe why structural
changes to genes (mutations) located on chromosomes may affect proteins and
may result in harmful, beneficial, or neutral effects to the structure and function of
the organism.

Disciplinary Core Ideas

MS-LS4.B Natural Selection: Natural selection leads to the predominance of
certain traits in a population, and the suppression of others.

MS-LS4.C Adaptation: Adaptation by natural selection acting over generations
is one important process by which species change over time in response to
changes in environmental conditions. Traits that support successful survival and
reproduction in the new environment become more common; those that do not
become less common. Thus, the distribution of traits in a population changes.

EVOLUTION  31

ACTIVITY 3  A MEETING OF MINDS

MS-LS3.BVariation of Traits: In addition to variations that arise from sexual
reproduction, genetic information can be altered because of mutations. Though
rare, mutations may result in changes to the structure and function of proteins.
Some changes are beneficial, others harmful, and some neutral to the organism.

Science and Engineering Practices

Constructing Explanations and Designing Solutions: Construct an explanation that
includes qualitative or quantitative relationships between variables that predict or
describe phenomena.
Engaging in Argument from Evidence: Use an oral and written argument supported
by evidence to support or refute an explanation or a model for a phenomenon.

Crosscutting Concepts

Cause and Effect: Phenomena may have more than one cause, and some cause and
effect relationships in systems can only be described using probability.
Patterns: Patterns can be used to identify cause and effect relationships.

Common Core State Standards—ELA/Literacy

RST.6-8.2: Determine the central ideas or conclusions of a text; provide an
accurate summary of the text distinct from prior knowledge or opinions.
WHST.6-8.9: Draw evidence from literary or informational texts to support
analysis, reflection, and research.

WHAT STUDENTS DO
Students role-play an imaginary meeting between Charles Darwin, Jean-Baptiste
Lamarck, a modern-day science reporter, and a middle school student. In the
role play, Darwin and Lamarck engage in scientific argument as they present and
compare their explanations for how a change in a species occurs. Students learn
that Darwin’s explanation has been accepted as the Theory of Natural Selection
and that this theory is essential to our understanding of evolution.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Scoring Guide: constructing explanations (exp)

■■ For each student

1 Student Sheet 3.1, Anticipation Guide: “A Meeting of Minds”
1 Literacy Student Sheet 4a, “Writing Frame—Constructing Explanations”

(optional)
1 Scoring Guide: constructing explanation (exp) (optional)

32 EVOLUTION

A MEETING OF MINDS ACTIVITY 3

Decide if you will have all students perform the role play in groups of four or if
you will assign the role play to one group to practice and present to the class; this
may be a group of students ahead with their work or students who have trouble
with written assignments but excel at performing. Because of the complexity of the
ideas contained in the role play, you may wish to have students do the activity both
in groups and then in a full-class format.

TEACHING SUMMARY

GET STARTED

1. The class uses the example of dogs to discuss inherited vs. acquired
(non-inherited) traits.
a. Ask students to consider the following scenario about dog breeding:
b. Encourage students to think about which of the two traits—the unusual
coat color or the trimmed ears—is more likely to be inherited by the
offspring.
c. Tell students that they will participate in a role play that discusses how a
species can come to look different after many generations.

DO THE ACTIVITY

2. (literacy) Students read the role play aloud.
a. Have groups of four or the pre-identified four students read through the
role play.
b. Consider having a brief discussion after students have had a chance to
read through the role play one time.
c. If appropriate, have your students read the role play again, either in their
groups or individually.
d. Distribute Student Sheet 3.1, Anticipation Guide: “A Meeting of Minds.”
e. Enhance sensemaking by having students complete the Anticipation
Guide.

BUILD UNDERSTANDING

3. The class reviews the key concepts.
a. Reinforce the distinction between Lamarckian and Darwinian evolution
by revisiting the story of the dogs.

EVOLUTION  33

ACTIVITY 3  A MEETING OF MINDS

b. Review the definition of an adaptation in the context of natural selection,
contrasting it with the everyday definition.

c. Direct students to Analysis items 1 and 2.

d. (exp assessment) Direct students to Analysis item 3.

TEACHING STEPS

GET STARTED

1. The class uses the example of dogs to discuss inherited vs. acquired
(non-inherited) traits.

a. Ask students to consider the following scenario about dog breeding:

“You breed dogs for a living.You own five adult dogs, all similar in
appearance. One of the dogs was born with an unusual coat color that
is highly desired by dog owners. Many people prefer these dogs to have
ears that stand up, and you had one of your dog’s ears “trimmed” so they
stand up.Your children are interested in breeding the dogs and selling the
puppies. Dogs with the unusual coat color and/or the ears that stand up
will sell for a higher price.Your daughter would like to breed the dog with
the unusual color because she thinks her puppies are more likely to have
that color.Your son would like to breed the dog with the trimmed ears
because he thinks her puppies are more likely to have ears that stand up.
What do you tell your children about breeding the dogs?”

b. Encourage students to think about which of the two traits—the unusual
coat color or the trimmed ears—is more likely to be inherited by the
offspring.

The dog with trimmed ears acquired this trait after it was born, just as
some humans acquire pierced ears. There is no reason to expect her
puppies to have such ears. The dog with the unusual coat color, however,
was born with that coloring. It is likely, though not certain, that this is a
genetic trait that may be passed on to her puppies. Use this example to
distinguish between inherited and acquired traits.

c. Tell students that they will participate in a role play that discusses how a
species can come to look different after many generations. 39

Inform students that in the 1800s, two different theories were proposed
about how species change over time; they will learn about these theories
in the role play.

39 NGCCPA1

34 EVOLUTION

A MEETING OF MINDS ACTIVITY 3

DO THE ACTIVITY

2. (literacy) Students read the role play aloud.40

a. Have groups of four or the pre-identified four students read through the
role play.

If the pre-identified four students will read the role play aloud, decide
whether you want others to follow along in the book or close their books
and listen.You might allow each student to choose which they think will
work for them.

b. Consider having a brief discussion after students have had a chance to
read through the role play one time.

Point out the mention in the role play of strong muscles developed
through exercise as an example of an acquired characteristic. This
example helps to address the misconception that acquired characteristics
can be inherited.

c. If appropriate, have your students read the role play again, either in their
groups or individually.

You may wish to point out that in this role play, Lamarck and Darwin
are engaging in a scientific argument. Each of them is arguing that their
explanation for how species change over time is the better one. Through
argumentation, scientists come to more accurate explanations for
observations and phenomena.

Encourage students to make notes and write down any questions they
have in their science notebooks.

d. Distribute Student Sheet 3.1, Anticipation Guide: “A Meeting of Minds.”4142

The role play is supported with a Directed Activities Related to Text
(DART) strategy, wherein students are provided with activities that are
related to the reading to help process the information. The questions allow
students to process and manipulate the information that they encounter in
the reading. For more information on DARTs, see the Literacy section of
Teacher Resources II, “Diverse Learners.”

e. Enhance sensemaking by having students complete the Anticipation Guide.

Have students complete the "BEFORE" column of the Anticipation
Guide individually. Follow this with small group discussions where group
members compare their ideas. Emphasize that students defend their argu-
ments by using scientific reasoning. Next hold a class discussion to come
to a consensus and ask groups to share any questions where the group

40 ELRS682
41 SELTIA1
42 ELWH689

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ACTIVITY 3  A MEETING OF MINDS

members disagreed. Finally have students complete the "AFTER" column
of the Anticipation Guide. Remind students that arguing in science is
an important practice that results in more complete and accurate expla-
nations for phenomena. Just as Darwin and Lamarck politely disagreed
with one another, students should respect other students’ explanations.
The goal is for students to be able to identify which of the statements are
consistent and inconsistent with Darwin’s theory.43

BUILD UNDERSTANDING

3. The class reviews the key concepts.

a. Reinforce the distinction between Lamarckian and Darwinian evolution
by revisiting the story of the dogs.

Ask students about the dog with the ears that were trimmed to stand-up:
“Which scientist—Lamarck or Darwin—would be more likely to argue
that this trait could be passed on to the dog’s offspring?” Students should
be able to answer that Lamarck believed in the inheritance of acquired
characteristics, whereas Darwin believed that only variation naturally
occurring at birth was inherited by subsequent generations.

Being able to understand the differences between Lamarckian and
Darwinian evolution relies, in part, on an understanding of genetic vs.
non-genetic traits. If students have not completed the Reproduction unit,
be prepared to review the use of the terms genes and traits, and to discuss
the difference between inherited and non-inherited traits.

b. Review the definition of an adaptation in the context of natural selection,
contrasting it with the everyday definition.

The role play explores what an adaptation really is: a trait typical of a
population, due to the favored survival and reproduction of individuals
with that trait. In particular, emphasize natural selection acting upon
pre-existing variation. To reinforce this point, you may want to remind
students that the source of variation in a population is naturally occurring
genetic differences. Be alert to students’ assertions such as, “The giraffe
evolves/adapts its neck to reach higher leaves,” which are a sign of
Lamarckian thinking.

c. Direct students to Analysis items 1 and 2.

Have students discuss their responses in their groups first, followed by a
class discussion. A firm understanding of these items will help students be
successful on item 3. Remind students about productive ways to engage
in scientific discussion by referring them to “Developing Communication
Skills,” found in Appendix E in the Student Book. 44

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3446  EVOLUSETSSIGOI2 N

A MEETING OF MINDS ACTIVITY 3

Also, see “Teacher Discussion Starters” in Teacher Resources II, “Diverse
Learners,” for guidance on how to facilitate whole-class or group
discussion.45

d. (exp assessment) Direct students to Analysis item 3.4647

Analysis item 3 is the first use of the constructing explanations (exp)
Scoring Guide in this activity. Optionally project or distribute the Scoring
Guide. Point out how it has the same levels as the previous guides but
different descriptions for each level. Review the levels as needed. For more
information, see Teacher Resources III, “Assessment.”

Consider distributing Literacy Student Sheet 4a, “Writing Frame—
Constructing Explanations,” if students need structured support with
writing scientific explanations.48

SAMPLE RESPONSES TO ANALYSIS

1. Compare and contrast Lamarck’s and Darwin’s theories of change over time. 49

a. What are the similarities? What are the differences?

Both Lamarck and Darwin thought that changes in species happened slowly,
over many generations. Lamarck thought that any body part of an individual
could change over the individual’s lifetime, and these changes could be passed
on to offspring.The accumulation of such events could make the entire species
look different over time. Darwin noted that individuals in a population differed
at birth. He proposed they could pass on only those traits they already had, not
the ones they acquired.The reason that populations looked different over time is
because some individuals had survived to reproduce more than others had, and
their traits were passed on.

b. Why do scientists find Darwin’s theory more convincing? 50

Scientists find Darwin’s theory more convincing because of evidence for how
characteristics are passed from one generation to the next.Variation within a
population can be observed.Today, the study of genetics has demonstrated that
many traits are, at least in part, inherited. However, acquired traits are not
inherited, since they do not affect the genes.Thus, the evidence has supported
Darwin’s theory while disproving Lamarck’s theory.

2. Explain why earthworms are beige or brown and not green5152

a. using Darwin’s theory of natural selection.

SELTDS1 Earthworms are beige because in previous generations, beige earthworms
46 NGSPCE2 were more likely to avoid being eaten by predators by blending in with the
47 SEASEX1
48 SELTWF1 EVOLUTION  37
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ACTIVITY 3  A MEETING OF MINDS

background.This makes sense because earthworms live in the dirt, which is
brownish black.These beige earthworms had offspring that were also beige.
Earthworms will continue to be beige until the environment changes.
b. using Lamarck’s theory of change.
Earthworms became beige or brown over time because they were living in dirt.
They kept changing their color until they blended in with the dirt.
3. (exp assessment) Explain whether Darwin’s theory or Lamarck’s theory is
a better explanation for your results in the previous activity, “Hiding in the
Background.”
Hint: Be sure to cite evidence from the activity. 5354

SAMPLE LEVEL-4 RESPONSE

Darwin’s theory better explains the results from the worm activity. In the activity,
individual worms were always either green or beige throughout their lives.They didn’t
change by living in either types of environment.The green population increased over
time not because of changes in individual worms, but because predators ate the beige
worms.There were more green worms at the start of the next generation, and they had
green offspring. Green worms became more and more common.

REVISIT THE GUIDING QUESTION
How does natural selection happen?
Individuals possess traits that they inherited from their parent(s). Some of these
traits make the individual well suited, or adapted, for the present environment.
This individual will be better able to survive and reproduce. This trait then
becomes relatively more common in the next generation. As the environment
changes, traits may be more or less suitable for the new environment.

ACTIVITY RESOURCES

KEY VOCABULARY
adaptation
evolve
gene
natural selection
trait

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38 EVOLUTION

A MEETING OF MINDS ACTIVITY 3

BACKGROUND INFORMATION

LAMARCKIAN VS. DARWINIAN EVOLUTION

Until the early years of the 19th century, most people believed that the history of
Earth was relatively short (less than 6,000 years) and that all species that existed
on Earth had always been present. Jean-Baptiste Lamarck (1744–1829) articulated
the first major theory explaining how species changed. Called the inheritance
of acquired characteristics theory, it was founded on the idea that frequent and
vigorous use of a body part led to a slight increase in its size. While this could be
observed in the case of muscle tissue, Lamarck applied this idea to all aspects of an
organism’s anatomy. Lamarck further proposed that these changes were heritable
and could lead an entire population to transform gradually over time. Due to
advances in genetics, it is now known that acquired traits are not inherited.

(Lamarck argued that his theory could also explain the shrinking of organs no
longer used, such as the human appendix. In fact, the application of natural
selection to vestigial organs can be subtle, as discussed below.)

An outline of Lamarck’s theory of evolution might consist of only two steps:

1. An organism’s use of an organ causes it to enlarge.

2. The offspring of that organism are born with larger versions of that organ.

In Lamarck’s view, individual organisms adapt to their needs as their bodies
become modified, however slightly; evolution occurs because as generations pass,
the population accumulates the results of those changes. Lamarck’s theory is often
misrepresented as teleological, or dependent on an animal’s will. (In fact, Darwin’s
theory is also misrepresented this way.) But Lamarck never argued that creatures
strove to better themselves or that an animal’s effort was what caused it to change.
Lamarck merely referred to what he thought was an obvious biological fact, at least
for certain aspects of a body: that frequent and rigorous use of a body part caused
it to enlarge (the opposite is seen, for example, in the well-known phenomenon of
muscle atrophy). He further assumed that such changes are inheritable.

Charles Darwin (1809–1882) and Alfred Russel Wallace (1823–1913), on the
other hand, argued that adaptations are acquired over many generations by a
population. Darwin, living long before the turn of the 20th century, was not aware
of Gregor Mendel’s work in genetics, which became understood by other scientists
only after chromosomes were discovered. Darwin was therefore unable to link the
appearance of new or modified traits with genetic mutations; he did not know that
there was a single source of all the variation in a population. His main contribution
was the observation that variation does exist within any population and provides
the raw material for a selective process.

EVOLUTION  39

ACTIVITY 3  A MEETING OF MINDS

(Interestingly, Darwin thought that variation might arise in numerous ways,
including the use and disuse of body parts—at that time, the scientific knowledge
did not exist to refute Lamarck’s position. Darwin’s goal in proposing natural
selection was to introduce a mechanism for change in the composition of a
population over generations, one that is powerful regardless of the source of
variation. He also extended evolutionary change to the diversification of species,
which he called descent with modification; this will be addressed in later activities.)

Darwin and Wallace’s theory, now more commonly known as natural selection,
can be summarized with the four steps below. Note that “survival of the fittest,”
the catch phrase for natural selection, is only one component of a process that,
like Lamarck’s, depends on the gradual accumulation of change over many
generations.

1. Variation within a species occurs naturally. (We now know this is due to
genetic mutations occurring during chromosome replication.)

2. Organisms must compete for limited resources to survive.

3. The individuals that are better fit for current environmental conditions (due
to their traits, which we now know are encoded, at least in part, in their genes)
survive and reproduce more often than the others do (“survival of the fittest”).

4. As a result, the genes and traits that are most common in a population can
change through time.

Even vestigial organs can be explained by Darwinian selection: If they persist for a
long time, the selective pressure for their shrinkage must be very small. However,
natural selection does eventually reduce even relatively harmless vestigial organs,
since individuals that more efficiently allocate their biochemical energy to useful
parts of the body have a selective advantage, however slight.

A challenge often posed to natural selection is the ubiquity of “poorly adapted”
traits in nature. These are readily explained by understanding evolution as a
process that occurs in context—not only in an environmental context, but also in
the context the genetic composition of a species. Only certain mutations occur at
any point in time, and natural selection can act only on the variation available in
the population.

EVOLUTION-RELATED MISCONCEPTIONS

Development is frequently misused as a synonym for evolution. Biological
development is the transformation over an individual’s lifetime from a zygote into
an adult organism. Though evolutionary change can gradually change the patterns
of development within a population, development and evolution refer to different
processes.

40 EVOLUTION

A MEETING OF MINDS ACTIVITY 3

The use of the term adapt can also be misleading. The noun adaptation refers
to a trait that increases an individual’s chance of survival and reproduction, and
has evolved due to selective pressure. The verb adapt is often incorrectly used to
describe the response of a single organism to the environment. More precisely, an
organism does not adapt physiologically to changing environmental conditions but,
rather, adjusts or acclimates. For example, in cold temperatures, your body shivers
and raises its metabolic rate. But a single organism does not “adapt”—to describe
it so is an inaccurate statement suggestive of a Lamarckian view of inheritance.
Because evolutionary history shows the development of life from simple to more
complex, there is often a tendency to assume that complex organisms are more
successful. Portrayals of evolution in the media constantly reinforce this idea,
especially with regard to humans as the pinnacle, or culminating, species. It is true
that increasingly complex life forms have appeared throughout recent geologic
history. But many of the simplest life forms (particularly bacteria) have survived
and proliferated on Earth for the longest periods of time, in the greatest numbers,
and in the most diverse environments. Simplicity is arguably the most successful
approach.

EVOLUTION AS HISTORICAL SCIENCE

One reason for public misunderstanding of evolution is that it is a historical rather
than an experimental science. Most of the data analyzed in studying evolution is
gathered (in forms such as fossil evidence and DNA sequence comparison) and
not generated. Nevertheless, as in any area of science, explanatory theories are
proposed and tested with data. Natural selection as a general theory has withstood
every scientific test to which it has been subjected.

EVOLUTION  41

Name______________________________________________________________ Date____________

STUDENT SHEET 3.1

ANTICIPATION GUIDE: A MEETING OF MINDS

After completing the role play, use the "BEFORE" column to mark whether you think
that today's scientists would agree (+) or disagree (–) with each statement below.
After finishing the class discussion use the "AFTER" column to mark whether you think
that today's scientists would agree (+) or disagree (–) with each statement below. Under
each statement, explain how the activity gave evidence to support or change your ideas.

I think that today's scientists would agree (+) or disagree (-) with:

BEFORE AFTER 1. If a bird population’s food source changes from soft berries to
hard seeds, birds with the variation of stronger beaks are more
______ ______ likely to survive than birds with weaker beaks.

______ ______ 2. Because the birds now have to eat hard seeds, their beaks will
grow stronger during their lifetime, and they will pass these
stronger beaks on to their offspring.

______ ______ 3. Because these birds have to eat hard seeds, the birds with the
strongest beaks will survive and reproduce; over time, the en-
tire population will have stronger beaks.

______ ______ 4. If an environmental change occurs, some individuals within a
population may have a physical variation that allows them to
survive better than others.

©2017 The Regents of the University of California ______ ______ 5. If an environmental change occurs, the entire population of
animals will physically change over one or more generations.

______ ______ 6. A parent who practices their free throw and can sink a basket
routinely will very likely pass the ability to sink free throws to
their child.

______ ______ 7. A parent who is a good athlete may pass the characteristic of
good coordination to their child.

Name_______S_a__m__p__le__s__tu__d_e__n_t__r_e_s_p__o_n__s_e___________________________ Date____________

STUDENT SHEET 3.1

ANTICIPATION GUIDE: A MEETING OF MINDS

After completing the role play, use the "BEFORE" column to mark whether you think
that today's scientists would agree (+) or disagree (–) with each statement below.
After finishing the class discussion use the "AFTER" column to mark whether you think
that today's scientists would agree (+) or disagree (–) with each statement below. Under
each statement, explain how the activity gave evidence to support or change your ideas.

I think that today's scientists would agree (+) or disagree (-) with:

BEFORE AFTER 1. If a bird population’s food source changes from soft berries to
hard seeds, birds with the variation of stronger beaks are more
___X___ ______ likely to survive than birds with weaker beaks.

______ ___X___ 2. Because the birds now have to eat hard seeds, their beaks will
grow stronger during their lifetime, and they will pass these
stronger beaks on to their offspring.

___X___ ______ 3. Because these birds have to eat hard seeds, the birds with the
strongest beaks will survive and reproduce; over time, the en-
tire population will have stronger beaks.

___X___ ______ 4. If an environmental change occurs, some individuals within a
___X___ population may have a physical variation that allows them to
______ survive better than others.
___X___
©2017 The Regents of the University of California ______ 5. If an environmental change occurs, the entire population of
___X___ animals will physically change over one or more generations.

6. A parent who practices their free throw and can sink a basket
routinely will very likely pass the ability to sink free throws to
their child.

______ 7. A parent who is a good athlete may pass the characteristic of
good coordination to their child.