Chapter 2 ALGEBRAIC EXPRESSIONS 40 Focus-on Mathematics Teacher’s Guide Grade 8 Closing Guide the whole class to conclude the concept of algebraic exprssxions. Go to page 57, summarise the key points covered in the lessons. Check for students’ understanding by asking questions or having a brief class discussion. Let students attempt Mastery Practice 2 (P57 – 59). Then, discuss about the answers with them. Mastery Practice 2 Answers: Section A 1. B 2. D 3. C 4. B 5. D 6. A 7. A 8. C 9. C 10. D Section B 1. (a) Variables: a Coefficients: –3 Constant: 7 (b) Variables: m Coefficients: 3 Constant: –11 (c) Variables: p Coefficients: 5 Constant: –2 2. (a) 1 (b) 3 (c) 2 (d) 5 (e) 4 3. Types Polynomial Cubic polynomial 4x + 3x2 Linear polynomial –3 + 5x Quartic polynomial 5x2 – 6 – x4 Quadratic polynomial 5x3 + 4x 4. 5. (a) 6y2 – 4y – 5 (b) 15x2 – 8x + 6 (c) 3w2 – 2w + 5 (d) 3s2 + 4s + 7 (e) –8pq + 6q2 (f) –3n2 + 4m2 + 2m – 5n + 9mn 6. x + x = 2x (x ) (x ) = x2 7. (a) 7x + 12 (b) 3x2 + 3x + 7 and x2 – x – 3 8. (Accept any possible answers.) 3x + 2x + x + 1 + 2 + 3 ©Praxis Publishing_Focus On Maths
Chapter 2 ALGEBRAIC EXPRESSIONS Focus-on Mathematics Teacher’s Guide Grade 8 41 Assessment At the end of this chapter, teacher needs to make sure that students should be able to • distinguish between monomials and polynomials. • determine the degree of a polynomial. • model polynomials using algebra tiles. • perform addition and subtraction involving polynomials. • perform multiplication and division involving polynomials. • determine the values of algebraic expressions. • apply the knowledge of algebraic expressions to solve mathematical problems and real-life problems. Materials • GeoGebra App • Focus-on Mathematics Textbook Grade 8 • Focus-on Mathematics Workbook Grade 8 • Focus-on Mathematics Grade 8 — PowerPoint 9. (a) 12h2 + 4h – 14 (b) –30k2 + 6k – 15 (c) –4ef + 4e2 – 4f 2 (d) –6c2 + 8c (e) 3 – 4y (f) –2x2 + 7x – 5 (g) −62−9 3 (h) –2s + 3 10. (a) 26x + 4 ; 134 cm (b) 24x + 9 ; 129 cm 11. (a) 6x + 4 (b) Length = 30 cm; Width = 40 cm; Area = 600 cm2 12. (a) 3 4 x – 6y2 (b) –30 13. a = 2 14. (a) Number of squares 1 2 3 Number of dots 7 11 17 (b) Un = 4n + 3 15. (a) n = 4 (b) U = 5n + 1 (c) (i) 51 (ii) 276 16. (a) 2n (b) 2n + 1 17. (a) J = 3p + 34 (b) 24 years old ©Praxis Publishing_Focus On Maths
42 Focus-on Mathematics Teacher’s Guide Grade 8 Objective To engage students in hands-on exploration of algebraic expressions and enhance their understanding of how expressions work. Materials • Index cards or small pieces of paper • Markers or pens • Whiteboard or chart paper • Math manipulatives (optional) Instructions 1. Begin by reviewing the concept of algebraic expressions and their components (variables, constants, operations). 2. Explain that in this activity, students will work in pairs or small groups to create and manipulate algebraic expressions. Create Expression Cards 3. Distribute index cards or small pieces of paper to each group. 4. Instruct students to create algebraic expressions on the cards. They can use variables (x, y, z), constants (numbers), and basic operations (+, −, ×, ÷). 5. Encourage creativity and variety in the expressions they create. The teacher can also create another set of cards and distribute them to the groups. 6. Have each group exchange their expression cards with another group. 7. Instruct students to simplify the expressions they receive by performing the indicated operations. They should write the simplified expression on a piece of paper. ©Praxis Publishing_Focus On Maths
STEM ACTIVITY: Exploring Algebraic Expressions Focus-on Mathematics Teacher’s Guide Grade 8 43 Expression Showcase 8. Display a whiteboard or chart paper in front of the class. 9. Invite each group to share one of their original expressions and its simplified form with the class. 10. Write down the expressions on the board and discuss the simplification process as a class. Extension activity: Manipulative Challenge 1. Provide math manipulatives or algebraic tiles (e.g., counters, cubes) to each group. The teacher can use this: https://mathsbot.com/manipulatives/tiles. 2. Assign a set of algebraic expressions to each group. 3. Instruct students to use the manipulatives to model the expressions and perform the operations. 4. Encourage them to visually demonstrate the steps of simplification. Reflection and Discussion 1. Lead a class discussion on the experience of creating and simplifying algebraic expressions. 2. Ask students to share any challenges they faced and strategies they used. 3. Discuss the importance of clear communication in algebraic expressions and the role of variables. Assessment Assess students' understanding through their active participation in creating, simplifying, and explaining algebraic expressions during the activity. Review their expression cards and their ability to simplify expressions accurately. ©Praxis Publishing_Focus On Maths