Do you subitize in your classroom? Here is a freebie to try it out. Project slides on your IWB, with your document camera, or print them out. After introducing students to the concept, flip through slides, starting at a rate of about 3 seconds per slide. The goal is for students to instantly count or recognize the number of dots on the slide.
It is an instant number sense builder, that you can complete in just minutes of classroom time. How often do you come across something like that?
For more information, check out my blog post here: