B2.2 understand the divisibility rules and use them to determine whether numbers are divisible by 2, 3, 4, 5, 6, 8, 9, and 10
Activity 1: Factor and Divisor of a Number
Present this situation to the students.
Mr. Theis has 36 red pens and 120 blue pens. He wants to divide all these pens into packets of red pens and packets of blue pens. He also wants to make sure that the number of pens in the blue pen bundles is the same as in the red pen packets.
- How many pens can he put in each bundle?
- What is the greatest number of pens he can put in each bundle?
To solve this problem, students can list the possible divisors of 36 and 120. By comparing the lists and deciding that 1 pen is not a "bundle", they can see that Mr. Theis can make bundles of 2, 3, 4, 6 or 12 pens and that 12 is the most pens he can put in a bundle. This type of problem prepares students for the concepts of greatest common divisor (GCD) or greatest common factor (GCF) that will be explored more thoroughly in later grades.
Source : Guide d’enseignement efficace des mathématiques de la 4e à la 6e année, p. 58.
Activity 2: Find the Divisors of a Number
Ask students to find all possible divisors of the following numbers:
- 21
- 24
- 40
- 41
Ask students questions such as:
- What are the rules of divisibility for?
- What rules of divisibility can be applied? How do you know?
- What regularities could be used to quickly determine the divisors of the number in question? Why or why not?