Cogito
Grade 3 Math · Chapter 1 · Lesson 8
Multiplying and Dividing by 3 and 4
Two more tables, built from ones you know.
10 problems · about 13 minutes · 3.OA.C.7, 3.OA.B.5
What this lesson teaches
The child recalls the 3 and 4 times tables, using doubling for the fours.
- Fours are double doubles.
- Threes are twos plus one more group.
- Division uses the same facts backwards.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Dividing by 2, 5, and 10: 40 ÷ 5 = ?
Answer 8
Why 8 × 5 = 40.
Review — Multiplying by 2, 5, and 10: 7 × 5 = ?
Answer 35
Why 7 × 5 = 35.
Warm Up
Straightforward practice. Get the method working first.
4 problems8 × 3 = ?
Answer 24
Why 8 × 3 = 24.
What is multiplying by 4 the same as?
Answer Doubling twice.
Why Doubling twice multiplies by 4.
6 × 3 = ?
Answer 18
Why 12 and one more 6.
7 × 4 = ?
Answer 28
Why Double 14.
Build It Up
The same ideas with more to keep track of.
2 problems24 ÷ 3 = ?
Answer 8
Why What times 3 makes 24?
36 ÷ 4 = ?
Answer 9
Why What times 4 makes 36?
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Tables: 6 tables each seat 4 people. How many people can sit down?
Answer 24 people
Why 6 × 4 = 24.
The Tricycles: 9 tricycles each have 3 wheels. How many wheels?
Answer 27 wheels
Why 9 × 3 = 27.