Cogito
Grade 2 Math · Chapter 6 · Lesson 1
Odd or Even
Pair them up and see if one is left over.
10 problems · about 11 minutes · 2.OA.C.3
What this lesson teaches
The child decides whether a group up to 20 is odd or even by pairing the objects.
- Pair the objects up to test a number.
- None left over means even.
- One left over means odd.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — 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.
Review — Subtracting Across a Zero: 405 − 137 = ?
Answer 268
Why 405 − 137 = 268.
Warm Up
Straightforward practice. Get the method working first.
3 problemsIs 18 odd or even?
Answer Even
Why 18 pairs up with none left over.
What does even mean?
Answer They pair up with none left over.
Why Even means every object has a partner.
Is 12 odd or even?
Answer Even
Why 12 makes 6 pairs.
Build It Up
The same ideas with more to keep track of.
1 problemIs 15 odd or even?
Answer Odd
Why 15 makes 7 pairs and one over.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsHow many pairs does 16 make?
Answer 8
Why Half of 16.
Sharing Socks: There are 14 socks. Can every sock find a partner?
Answer Yes. 14 is even.
Why 14 makes 7 pairs with none left over.
The Team: 11 children want to work in pairs. Will anyone be left out?
Answer Yes. One child is left over.
Why 11 is odd, so one child has no partner.