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Elementary Mathematics

Lesson 105

Even and Odd Numbers

Pairs or not?

Even and odd

13 socks are paired; one has no partner, so 13 is odd.

Even and odd

Make pairs.12 make 6 pairs: 12 is even.13 leaves one alone: 13 is odd.
Even and odd.
Teacher controls

Conceptual model: a simplified teaching picture.

Controls
Pair twelve socks, then try thirteen socks.

Which number leaves one sock alone?

Which number leaves one sock alone?

Even numbers make pairs with none left over; odd numbers leave one.