I’m currently working with my Kinders and Firsties on subitizing. If you’re scratching your head about the word “subitizing”, you might not be alone. Consider this–how many fingers are displayed in the picture above. I’m pretty sure you answered eight. I’m also reasonably sure that you did not count the fingers one by one. That, my friends, is subitizing. Subitizing is a standard in both Kindergarten and 1st grade in Texas, although the TEKS don’t specifically mention the word:
K.2.D Recognize instantly the quantity of a small group of objects in organized and random arrangements
1.2.A Recognize instantly the quantity of structured arrangements
Subitizing allow students to move away from counting by ones to seeing numbers as chunks. For example, in the picture above, eight is seen as a chunk of five (the fingers on one hand) and three more. That’s much quicker than counting each finger. It also leads to a student understanding that 5 + 3 = 8.
So what are organized or structured arrangements? The pips on dice are a great example of an organized or structured arrangement. We instantly recognize the way the numbers look as represented by the pips on a die.
Another great structural tool is the ten-frame. First, we want students to recognize that if a row is full, it’s five and can be counted as five without counting each dot. That’s a huge step! I call it a “fast five”. Once they recognize that the full row is five, students can begin to count on. We run our finger across the top row and say “5” and then point to each dot as we count on (6, 7, 8). In time, the students will just recognize that the arrangement shows 8. Some might look at the empty spaces and know that two empty spaces means 8. Asking students how they know it’s eight is a terrific formative assessment, and one you can’t get with a paper and pencil activity. Think about what each of the following responses means in terms of understanding and number sense:
I counted all the dots.
I said 5…6, 7, 8
I know that 5 and 3 is 8
If all the spaces were full it would be 10, but 2 are empty so it’s 8
I can’t overstate how much practice Kindergarten and 1st graders need with this skill. It should be a part of your daily math instruction all year long. I keep my ten-frame flash cards on an O-ring, so I can easily grab them and spend a couple of minutes subitizing. In addition to ten-frames, students also need experience with different types of arrangements. I made a little I Have/Who Has game for practicing arrangements up to the number twelve. There’s only twelve cards in the set, so either use it for small group instruction, or use partners for whole group.