These 20 cards help students practice identifying prime numbers. The cards each contain four numbers. Students need to find the one that is prime. During this activity students will have to recognize numbers that look prime, but aren't. 51 and 57 are two examples. The cards are set up so that students will see how numerical patterns play into the dsicovery of prime versus composite. These can be placed in a math center, used as a SCOOT activity, or used as direct instruction from a document camera. Meets both Common Core and TEXAS TEKS.