C2.2 Evaluate algebraic expressions that involve whole numbers.
Activity 1: A good cause
Fifth graders decide to hold a fundraiser to help the local soccer team. The student council offers an initial contribution of $20. The Grade 5 students then invite students from across the school to come and stick one or more $2 coins, next to each other with no gaps, on a large strip of paper. The relationship between the number of coins and the amount raised is represented by the algebraic expression 2p+ 20, where p is the number of coins.
Ask students the following questions:
- How much money will be raised if 27 coins are stuck to the wall? 50 coins? 105 coins?
- Why do we have to add 20 to the total amount collected?
Activity 2: Decorative tape
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 (l) is represented by the algebraic expression 7f.
| Number of figures, f | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Number of tabs, / | 7 | 14 | 21 | 28 | 35 |
Ask students the following question:
- How many wooden strips are required if the decorative strip contains 58 figures, 70 figures, 100 figures?
Source: inspired by L'@telier - Online Educational Resources (atelier.on.ca).