What are you counting by when you skip like this?

Counting 5, 10, 15, 20 means you're counting by fives, adding five more each time instead of counting every single number one by one. This is a quick way to count things that naturally come in groups of five, like fingers on one hand or nickels in a piggy bank.

Counting by threes would instead go 3, 6, 9, 12, and counting by sevens would go 7, 14, 21, 28 — both add a different amount each jump, so neither matches the 5, 10, 15, 20 pattern shown here.

Skip counting by fives is one of the first tricks kids learn for counting large groups fast, and it's also a handy first step toward understanding multiplication later on.