### Subitizing - a video review

What is "subitizing"? It's probably a new word for most. It basically means being able to recognize instantly how many objects you see, without counting.

We all do that with the dots on the face of a dice. People who play dominoes with the larger set also learn to do that with the dots on the dominoes (they can go up to 18).

But why would such be important? It is for children, because it promotes number sense, and also ties in with the concepts of addition, subtraction, and even place value.

Look at the dominoes in the picture, and especially the one in the front with turquoise dots on the left side and three orange dots on the right.

Photo courtesy of catheroo

Looking at the turquoise dots, can you tell how many there are without counting?

Most of us realize that it is just one less than three rows of three, or nine. So therefore it has eight dots. That is "subitizing".

By learning to subitize a child is learning:
• number sense
• to associate a number with a whole collection
• to visualize quantities and the associated number
• relationships between numbers
• to visualize subsets of a number
• to use subsets of numbers to quickly make addition and
subtraction equations
• the foundation for quick and creative mental arithmetic
• place value concepts

I recently had the opportunity to watch a video made specifically to address this math concept, called Subitize Me! It is about 28 minutes long and meant for children from PreK to 2nd or 3rd grade.

This is the trailer of the video:

In it, two children go through an adventure of sorts inside ancient ruins where they have to first be able to tell the number of gold coins before they can escape. The children get there through a series of seven "lessons", for example with dice, with a snowman, or spacecraft. In each lesson they learn more and more about subitizing, until finally they are able to see the large number of coins in groups of ten tens (hundred) and groups of tens.

My children liked the movie and wanted to watch it twice (thus far). It is actually recommeded to watch it repeatedly over time so children can cement the concepts shown in the video.

This is a commercial movie on a DVD. The DVD also has some additional exercises for children to watch and think through. You can also purchase (separately) a booklet for the teacher that has activities you can do and has a brief summary of the movie.

The video is well made and ties in with the math concepts very well. I would recommend it to elementary school teachers, libraries, co-ops, math clubs and any such places where many children have the opportunity to watch it.

I'm definitely not against home users (parents) purchasing it, either. This concept is beneficial for all children and teachers! However, I consider it a bit pricey, as compared to other math-related movies and DVDs that are available commercially, because it does not really cover that big a part of the typical math curriculum. So you need to consider your budget. Maybe you could resell it afterwards, which would reduce the cost.

I also hope they would make it available for watching online for a small fee, kind of like how you can "rent" (download) movies from Amazon for a few dollars. That would make it more accessible to larger numbers of parents.

Beckie Russell said…
When we learn to recognize the value of a die face or of a dominoe, aren't we really just learning another numeral to represent the quantity? Because the arrangement of dots is important (and systematically used in dice, dominoes and playing cards), really the arrangement itself becomes a symbol for the quantity. So, when we see a group of 8 objects not arranged in the pattern we are used to, do our brains recognize it as 8 without doing some quick calculating on its own (like arranging them into groups of 4 or something)? Or can we immediately recognize it as 8 without any additional help? Perhaps I'm not fully understanding what "subitize" means.
Maria Miller said…
I feel that could be true. However, I think a lot of the value of subitizing is indeed in those quick calculations, when children can learn to notice that hey, in this pattern I can add such and such, or subtract such and such, to find how many there are.
Anonymous said…
Interesting post! In response to Beckie's comment from what I read at
http://www.k-5mathteachingresources.com/ten-frames.html

there are two types of subitizing: perceptual and conceptual. Perceptual subitizing is when we see a dot pattern and instantly recognize it without using other mathematical processes. For example, a child as young as two might “see 3” without using any learned mathematical knowledge. Conceptual subitizing is being used when the number pattern is recognized as a composite of parts and as a whole. For example, a domino with 8 dots is seen as being composed of two groups of four and as “one eight”.
unclegus said…
Beckie Russell is spot on. Subitising is the recognition of small numers of objects (0 to 4 usually, and yes I include 0 since it is undoubtedly the first number) regardless of their arrangement. It is an inate ability.
Recognising larger numbers in particular patterns such as six on a die is a learned behaviour and is NOT subitising. Nor is saying 3 + 3 = 6 as in the video. We can recognise each of the groups of three by subitising but combining them to make get six uses learned results of arithmetic combination.
Bon Crowder said…
Since "subitize" is from the latin "subitus" meaning "sudden" it really isn't well defined. You can certainly say we subitize words because we don't sound them out.

So if you suddenly are able to group bits and "add" them (via conceptual subitizing) you're still subitizing.

The 2-4 subitizing is the quickest and most valuable (imo right now).

0 and 1 are harder because they aren't immediately useful to a kid. If you have none, why would you bother mentioning it. And if you have 1, so what? This starts to play out more when there is ONLY 1 shoe (and they know there should be two) or NO cookies (and they think there should be many).

In an effort to create a non-video subitizing lesson (and free) I've made some subitizing flashcards that can be printed as 4x6 pictures. You can find them here: http://mathfour.com/sets-and-counting/how-to-teach-subitizing-up-to-4

Thanks Maria for the article and thanks Beckie and unclegus for the contributions. I SO love this topic!