Best Seller! Notched corners for quick organization. Large, easy to handle 6-1/4 x 3-1/4 cards. Bold, heavy type to use with large groups. Durable, thick card stock (14 pt.). Self-checking. Great for small groups, pairs, and whole class participation. Great for teaching the relationship of +/- and x/÷ (Example: 3 x 1 = 3 on one side, 3 / 3 = 1 on the reverse). Each box contains 90 classroom-size flash cards. Ideal for grades 2-4. Bundle of 3 Flashcard packs.