Mini-size positive reinforcer cards are great for teams/groups of students. I created these after taking a Cooperative Learning class based on Kagan Structures. I printed these sheets out on different colors of paper, mixed them up, and gave each group a baggie full of these cards. After certain activities, I would prompt the students to get out their Praise Cards and choose one to tell to a teammate/group member. After a while, the students used these automatically and without reminders - and even praised one another without using the cards.