Subitizing with Coloured Beans
The brain is designed to subitize (know how many in a small group without counting) and also to compare groups based on ideas of how many and how much.
In this picture, the first image shows one subitizable group and the second has two subitizable groups. That’s a good starting point - The beans can be shown just as a single group to be subitized or as two groups to promote the subitize and count on strategy.
There’s no reason not to extend the number of subitizable groups to three or beyond to match a learners current mental computation level.
Remember to stretch students and to listen to their reasoning.
“I think I saw 5 and 4 and 5. Double 5 is 10, a friendly number and 4 more is 14.”
If a student makes an error, don’t say yes or no but ask:
“Would you like to check?”
“Show me what you saw?”
We need students to feel confident to take a risk, check and fix up if necessary. We don’t want to promote maths anxiety by focusing only on the correctness of anwers.
As mental computation strategies are developed doubles, rainbow facts and near doubles can be presented as subitizable groups.
Barrier Game: How Many Beans?
The idea of the game is to make a small collection of beans (within range of the player) behind a book or similar barrier such that the other player cannot see them. The book is then briefly lifted and then replaced as a barrier. The other player can look very briefly at the arrangement of beans and say how many they think there are. The beans are then revealed and can be checked by a longer look or by counting. A high five is then made to congratulate a correct subitize or to congratulate a player who made a ‘tricky one’. Keep it fun and a positive experience.
It is important for students to swap roles and take turns because it is one thing to spot a subitizable pattern and quite another to deliberately create subitizable groups. We often sign off too soon. Students need to be able to spot, name and create subitizable patterns and know when to use them before we think the job is done.
For lots more ideas for subitizing see our award winning Subitizing series.
Take Home Activity
When the students are used to the sequence for How Many Beans? they can take a little bag of beans home and challenge their family. END OF DAY2