Knowing how many without counting. Subitizing – recognizing the number of objects in a group without having to count the objects is a fundamental building block for developing number sense. These simple 4.75″ x 7.75″ dot cards help students learn subitizing and understanding the crucial concept of making ten. The reverse side of the cards features the number word and numeral for instant reinforcement. Teachers use the cards with groups, follow-up practice in centers or for individualized self-check activity. 38 two-sided cards.