Cogito
Grade 2 Math · Chapter 6 · Lesson 2
Two Equal Addends
Every even number splits into two equal halves.
10 problems · about 11 minutes · 2.OA.C.3
What this lesson teaches
The child writes an even number as the sum of two equal addends.
- An even number splits into two equal parts.
- 14 = 7 + 7.
- Odd numbers always leave one over.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Odd or Even: Is 18 odd or even?
Answer Even
Why 18 pairs up with none left over.
Review — Word Problems Within 1,000: 462 + 289 = ?
Answer 751
Why 462 + 289 = 751.
Review — Adding Up to Four Numbers: 13 + 27 + 20 = ?
Answer 60
Why 40 + 20 = 60.
Warm Up
Straightforward practice. Get the method working first.
3 problems14 = ? + ? What is each part?
Answer 7
Why 7 + 7 = 14.
Which numbers can be split into two equal parts?
Answer Even numbers.
Why Only even numbers split into two equal whole groups.
12 = ? + ? What is each part?
Answer 6
Why What doubles to 12?
Build It Up
The same ideas with more to keep track of.
1 problem20 = ? + ? What is each part?
Answer 10
Why What doubles to 20?
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsCan 17 be written as two equal parts?
Answer No. It is odd.
Why Nothing whole doubles to 17.
Two Teams: 18 children split into two equal teams. How many are on each team?
Answer 9 children
Why 9 + 9 = 18.
Sharing Fairly: Can 13 sweets be shared equally between two people?
Answer No. 13 is odd.
Why One sweet would always be left over.