A long list of different warm up activities, none of which involve equipment so they can be carried out quickly and easily.
Stuck in the Mud
Stuck in the mud is a classic game and is a great pulse raiser for any age.
Two people are 'on' (that is depending on the size of the class - my example is for a class of 15-23 students). They have to chase the people that are not 'on' and tag them.
When they have tagged another student who was not on, that person is 'stuck in the mud'. They stand with legs and arms out and they cannot move. The only way to release them is if another person who is not stuck goes under the student that is stuck to free them. They can go through the person's legs, or under their arms.
This continues for about 5-10 minutes or until everybody is stuck. To increase the difficulty level, use more catchers.