Transcript:

The word “subitizing” has become familiar to lots of primary teachers; not all teachers at upper grades know that word because they don’t use it as much.

But essentially subitizing is really about knowing how many there are without actually having to count, to say, “1, 2, 3, 4, 5 …”

Now, I don’t know if you’ve heard about this, but I think it’d be valuable to be aware that there are really two different kinds of subitizing. One is called perceptual subitizing. It only is for small numbers, and it’s just that you look and you just know it’s 3 because it looks like 3; you don’t have to count, you just know it’s 3.

Most studies of subitizing have worked with very young kids, and they see that they actually can distinguish numbers like 2 and 3, some people say up to 5 or 6, without counting. They just look and know, and that’s great.

But a lot of what we do in math is actually what I would call conceptual subitizing. And that means that we arrange things in such a way that we can look and know without counting, even though there’s a lot more things.

So, for example, we teach kids to use the 10-frame because we can see, say, 8 in a 10-frame and immediately know it’s 8 without counting, because it’s a familiar arrangement; we see that it’s 2 missing from 10, so we know that it’s 8. Or if you want to see 9 and you arrange 3 rows of 3, you don’t have to count everything, because you know there’s 3, 6, 9.

So, we have what we call conceptual subitizing as well as perceptual subitizing, and that’s what we want to build on in our math curriculum.