B2.5 Represent and solve problems involving the addition and subtraction of whole numbers that add up to no more than 1000, using various tools and algorithms.
Activity 1: Problem Solving
Ask students to solve the following problems in 2 different ways.
Change (Join) Problem
John must collect 500 recyclable bottles to win a computer game. He already has 138 bottles. How many bottles does he need?
Compare Problem
The red team has read 674 books and the yellow team has read 328. Find out how many books the yellow team must read to have read the same number of books as the red team.
Join and Separate Problem
Thomas found 123 fossils. He found 456 more the next day, but lost 98. How many more does he have?
Change (Separate) Problem
Joanne had a lot of chalk. She gave 106 pieces to Francine. Now she has 329 left. How many did she have at the beginning?
Combine (Part-Part-Whole) Problem
At the zoo I saw 30 monkeys, 21 elephants, 44 penguins and 19 bears. How many animals did I see?
Source: translated from L’@telier - Ressources pédagogiques en ligne (atelier.on.ca).
Activity 2: Counting to Compare
Have students solve the following compare problem using various algorithms.
Here is the sales table of the factory A Thousand Delights:
| Day of the Week | Number of Cupcakes Sold |
|---|---|
| Monday morning | 263 |
| Monday afternoon | 489 |
| Tuesday morning | 341 |
| Tuesday afternoon | 138 |
The factory sells 263 cupcakes on Monday morning and 489 cupcakes on Monday afternoon. How many more cupcakes were sold in the afternoon? Show how you solved the problem.
The factory sells 341 cupcakes on Tuesday morning and 138 cupcakes on Tuesday afternoon. How many more cupcakes were sold in the morning? Show how you solved the problem.
On what day were the fewest cupcakes sold? How do you know? Show your thinking.