Every number is either odd or even. The simplest explanation is odd numbers can never be divided into two equivalent groups while even numbers can always be divided into two equivalent groups.
Parents and teachers can help early elementary age children learn to distinguish between odd and even numbers, using games and activities. Look around, let your kids to find anything that can count. Pillows, socks, shoes, shirts. Tell kids to place them in pairs and check out what is left behind. Those in pairs are even, while the left over is odd.
Fun idea:
https://learning.covoji.com/math-zon...t-odd-or-even/