Cogito
Grade 3 Math · Chapter 1 · Lesson 1
Equal Groups and Multiplication
A short way to write repeated addition.
8 problems · about 12 minutes · 3.OA.A.1
What this lesson teaches
The child interprets a product as the total number of objects in equal groups, and writes it with the multiplication symbol.
- Multiplication is a short way to add equal groups.
- 3 × 4 means 3 groups of 4.
- The answer is called the product.
Warm Up
Straightforward practice. Get the method working first.
4 problems4 groups of 5. What is the product?
Answer 20
Why 4 × 5 = 20.
What does multiplication do?
Answer Adds equal groups the short way.
Why Multiplication only works when the groups are the same size.
3 groups of 5. What is the product?
Answer 15
Why 3 × 5.
2 groups of 8. What is the product?
Answer 16
Why 8 + 8.
Build It Up
The same ideas with more to keep track of.
2 problemsIn 7 × 4, how many groups are there?
Answer 7
Why The first number.
In 7 × 4, how many are in each group?
Answer 4
Why The second number.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Bike Rack: 6 bicycles are parked. Each has 2 wheels. Write this as a multiplication and solve it.
Answer 12 wheels
Why 6 × 2 = 12 wheels.
The Egg Boxes: 4 boxes each hold 6 eggs. How many eggs are there?
Answer 24 eggs
Why 4 × 6 = 24 eggs.