My students will never have to stress over forgetting what a prime and composite number are after I finished with them this year! :) We practiced, then practiced some more. One activity we completed in class was a cut-n-paste activity where the kids had to decide whether each of the numbers was prime or composite number, and glue either a P or C over each number. This activity was completed after making sure we had plenty of experience with prime and composite numbers. The kids enjoyed this activity, and I am fairly certain our custodian, Missy, loves this cut-n-paste activity since there is really only 1 scrap of paper left over after the activity is completed. Once the paper is cut on the dotted line, the students cut out the P's and C's in one big square, then cut the individual pieces out with no scrap paper in-between.
You can find the handout Prime or Composite? along with many other activities, handouts, and mini-posters in my TPT store, Mrs. C's Classroom.