Here's a fun little activity that I picked up at a Pre-AP Summer Institute a few years ago. I'll be doing this specific version with my pre-cal students on Wednesday.
One set of games cards for each student
One set of questions
Have students arrange their game cards on their desks
Ask questions from the set of question cards, directing students to hold up the most complete correct answer
Students who answer incorrectly will remain in their seats
Students who answer correctly will proceed to the next available seat, "leap frogging" over the students who were incorrect
Play continues until a student returns to his/her original seat
The set I posted above covers vocabulary associated with function behavior. Additional applications include:
Create student game cards containing appropriate vocabulary words or math terms, reading the definitions to the students
Create student game cards with various numbers that work as solutions to equations you ask them to solve
Create student game cards with common trigonometric values on them, and then ask students to evaluate trigonometric expressions.
Ideally, the problems can be done quickly with a minimal amount of pencil-to-paper work.
If you are pressed for time (or your classroom layout doesn't really accommodate the "leap-frogging") you can just make one set of game cards for each group and have them hold up the correct answer in the group. Then just award points for each correct answer.