Common Core: Be Wise-Subitize, Developing Instant Recognition for Quantities. The ability to subitize, or instantly recognize small arrangements of items, is a foundational math skill. A few minutes of highly engaging practice each day is all it takes to develop this skill. This group of cards includes dice patterns, tally marks, hearts, and finger patterns. Includes instructions for how to use the cards in the classroom. Great for whole group or small group instruction. $
I would make this more challenging for my students by having kids work in pairs. Each child drops in a "secret number" of items into their cup. Then, they count the total number of items in the basket and try to guess how much the other child dropped in.