C2.2 Evaluate algebraic expressions that involve whole numbers.
Activity 1: A Good Cause
Students in Grade 5 decide to hold a fundraiser to help the local soccer team. The student council offers an initial contribution of $20. The students then invite other students from the school to contribute one or more toonies. Students arrange the toonies next to each other with no gaps, on a large strip of paper. The relationship between the number of toonies and the amount contributed is represented by the algebraic expression 2n+ 20, where n is the number of coins.
Ask students the following questions:
- How much money will be raised if 27 toonies are on the strip of paper? 50 coins? 105 coins?
- What does 20 in the algebraic expression represent?
Activity 2: Decorative Strip
A decorative strip for a wall is created using wooden strips of equal lengths forming a figure that is repeated several times. All figures are glued together.
The table of values below shows the quantity of wooden strips required for one figure, 2 figures, 3 figures, 4 figures and 5 figures. The relationship between the number of figures (f) and the number of strips (s) is represented by the algebraic expression 7f.
| Number of figures, f | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Number of wooden strips, s | 7 | 14 | 21 | 28 | 35 |
Ask students the following question:
- How many wooden strips are required if the decorative strip contains 58 shapes, 70 shapes, 100 shapes?
Source: translated from and inspired by L'@telier - Ressources pédagogiques en ligne (atelier.on.ca).