Cogito
Grade 3 Math · Chapter 1 · Lesson 10
Multiplication and Division Word Problems
Deciding which operation the story needs.
10 problems · about 14 minutes · 3.OA.A.3
What this lesson teaches
The child chooses between multiplication and division for equal-group word problems within 100.
- Find the three numbers: groups, size, and total.
- Total missing means multiply.
- Total known means divide.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
1 problemReview — Multiplying by 0 and 1: 7 × 0 = ?
Answer 0
Why Seven lots of nothing is nothing.
Warm Up
Straightforward practice. Get the method working first.
4 problems5 boxes with 8 pens each. How many pens?
Answer 40
Why 5 × 8 = 40.
The total is known and the group size is missing. What do you do?
Answer Divide.
Why A known total with a missing part means division.
"7 bags with 4 apples each. How many apples?"
Answer Multiply.
Why The total is what is missing.
7 bags with 4 apples each. How many apples?
Answer 28
Why 7 × 4.
Build It Up
The same ideas with more to keep track of.
2 problems45 sweets shared between 9 children. How many each?
Answer 5
Why 45 ÷ 9.
24 chairs in rows of 6. How many rows?
Answer 4
Why 24 ÷ 6.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsThe Bookshelf: 8 shelves each hold 5 books. How many books altogether?
Answer 40 books
Why 8 × 5 = 40.
The Cupcakes: 36 cupcakes go equally into 4 boxes. How many in each box?
Answer 9 cupcakes
Why 36 ÷ 4 = 9.
The Teams: 30 children make teams of 5. How many teams are there?
Answer 6 teams
Why 30 ÷ 5 = 6 teams.