Grades K–2 · Mathematics
Why can making pairs leave one thing over?
Shoes come in pairs: two shoes together. Small counters can make pairs too. Each counter goes beside one partner. A pair always has two counters.
In the diagramTwo in each pair7 counters3 pairs and 1 left overOdd: one counter has no partner.
With six counters, there are three pairs and none left over. Six is an even number. With seven counters, there are still three pairs, but one counter has no partner. Seven is an odd number. Adding one more counter gives that last counter a partner. Eight is even.
The counters do not have to be the same color to make pairs. It is the number of counters that matters. Even means they can all go into pairs. Odd means one is left. With zero counters there are no pairs and none left over, so zero is even too.
About this explanation
Starting knowledge: Can count small groups and understands two things together.
Sources
- University of Cambridge NRICH — Even and Odd