B2.4 Use objects, diagrams, and equations to represent, describe, and solve situations involving addition and subtraction of whole numbers that add up to no more than 100.
Activity 1: How Much Money?
Group students into pairs.
Present students with the following problem:
Beatrice had 50¢ in her piggy bank. Her grandmother gave her some money because she ran an errand for her. If
Beatrice now has 95¢, how much money did her grandmother give her?
Provide each team with a large sheet of paper and markers. Ask students to write down their reasoning. Provide manipulatives for students to use.
Allow students enough time to try more than one counting strategy.
Gather the students and ask each team to present its approach.
Activity 2: Organizing a Party
Present students with the following problem:
We are having an end of the year party for the students in the class. We want to decorate the room with streamers and balloons. We have 2 packages of streamers and 27 balloons. We need 55 balloons to properly decorate the classroom. How many more balloons do we need to buy?
Provide each team with a large sheet of paper and markers. Ask students to write down their reasoning. Provide manipulatives for students to use.
Allow teams enough time to try more than one counting strategy.
Gather the students and ask each team to present its approach.
Activity 3: What is the Problem?
Ask students the following question:
Can you write a problem that requires the following operation: 25 - 14?
Provide each team with a large sheet of paper and markers. Ask students to write down their reasoning. Provide manipulatives for students to use.
Allow teams enough time to try more than one counting strategy.
Gather the students and ask each team to present its approach.
Allow all students to state their problem.
Possible statements:
- I had 25 pieces of candy and I gave 14 to my friend, Nathan.
- I had 25 marbles and 14 rolled under the couch.
- I had 25¢ and spent 14¢ on a lollipop.
Give students other similar problems at regular intervals.
Ask a few students to write their problem in the collective math journal.
Source: Guide d'enseignement efficace des mathématiques de la 1re à la 3e année, p. 142-143.