What is subitizing? For those who are in upper elementary, this might be a concept you’re unfamiliar with. Basically, subitizing refers to the ability to recognize the number of objects in a group without counting. This is a foundational skill necessary to build strong number sense.
I have used a number sense warm up called “guess how many?” in a few classrooms that addresses this skill. We put some dots up on the projector and the kids had 5 seconds to look and then guess how many. It sounds short but 5 seconds was a long time- so many kids just guessed! I worked with the teachers to increase the number of dots and decrease the amount of time- you’d have to do what works for you and your students.
I recently came across this page by Graham Fletcher. Not only has he created an outstanding game with so many possible applications, but he also shows videos of these activities in use by students of varying ages and abilities. He created a series of cards with geometric shapes that you can download right from the site. Check it out here.
Have you used geometric shapes to help your students subitize numbers? How did it work for you? I’d love to hear from you if you have any thoughts about this!
Math Coach Corner 