Subitizing: instantly seeing how many.
Show one card to the students, but only give them 2 or 3 seconds to look (what I do for kindergarteners). Then call on students to share their number. In the packet I have a page on how to call on students and what questions to ask.
This product includes 48 ten-frame cards. I recommend printing on cardstock and laminating so they will be sturdy and last longer.
This activity is perfect for whole class, small group, or even partner practice.