Skip-Counting for Numeracy
Most kids learn, in kindergarten or first grade, to count by 2’s, 5’s, 10’s. By rote. This has its uses, but going beyond that level of skip-counting can make great numeracy practice, and it seems to be quite under-used.
In our school, we have the primary kids skip-count by 2’s starting from numbers other than 2. Then they practice skip-counting by other numbers, again starting at arbitrary places. Forward and eventually backward. This is an easy one to differentiate, because you can have some kids counting up by 2’s and others counting backward by 7’s at the same time. 🙂 Eventually skip counting is used to introduce multiplication.
Today I asked the intermediate group (approx 3rd – 5th grade math levels) to do some skip-counting for me, forward and backward by 2, 3, 5, 10, 20, 25, 50, 100 and 99! Boy that last one was a doozie! (“Can we use calculators?”) But all of it was clearly good practice even for these “big kids”. For counting (up) by 99’s, they quickly realized that they could add 100 and then subtract one. But a LOT of them got stuck crossing the 1000 boundary (going from something like 987 to 1086). I didn’t think of it at the time, but now I think that pointing out that 1000 is really the same as “ten hundred” might be helpful for a lot of them. Now backward by 99’s was really tricky! So… you first subtract 100 and then… what? Only one of the 6 kids I was working with today (only half of the usual group) really understood that you would then have to ADD 1 back. “I’m taking away a little LESS than 100, so should the answer be a little more or a little less than what we got by taking away a whole hundred?” This is not intuitive for a lot of kids!
So, if you’re working with elementary school aged kids, skip count! Regularly! I think it’s a key skill for developing number sense.