Cogito
Grade 2 Math · Chapter 6 · Lesson 3
Equal Groups
Groups that all hold the same number.
10 problems · about 12 minutes · 2.OA.C.4
What this lesson teaches
The child finds the total of several equal groups by repeated addition.
- Equal groups all hold the same number.
- Add the group size once for each group.
- If the groups differ, this does not work.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Two Equal Addends: 14 = ? + ? What is each part?
Answer 7
Why 7 + 7 = 14.
Review — Odd or Even: Is 18 odd or even?
Answer Even
Why 18 pairs up with none left over.
Warm Up
Straightforward practice. Get the method working first.
4 problems5 groups of 4. How many in all?
Answer 20
Why 4 + 4 + 4 + 4 + 4 = 20.
What must be true of the groups?
Answer They all hold the same number.
Why Equal groups must match exactly.
3 groups of 5. How many in all?
Answer 15
Why 5 + 5 + 5.
4 groups of 3. How many in all?
Answer 12
Why 3 + 3 + 3 + 3.
Build It Up
The same ideas with more to keep track of.
2 problems2 groups of 5. How many in all?
Answer 10
Why 5 + 5.
One plate has 4 buns and another has 6. Are these equal groups?
Answer No. They hold different numbers.
Why Equal means the same number in each.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Bike Rack: 5 bicycles are in a rack. Each has 2 wheels. How many wheels?
Answer 10 wheels
Why Five groups of 2 is 10.
Packs of Pens: 4 packs each hold 5 pens. How many pens in all?
Answer 20 pens
Why Four groups of 5 is 20.