Example: In this example, I have just taught 4 colours (Red, Yellow, Blue and Green).
Touch S1 on the head and say "Red" (get the S to repeat).
Touch S2 on the head and say "Yellow" (get the S to repeat).
Touch S3 on the head and say "Blue" (get the S to repeat).
Touch S4 on the head and say "Green" (get the S to repeat).
When you get to S5, just start again from "Red"
Make sure the students know their vocab: Say "Stand up, Red" - I say the action first so that all the students listen. Continue until you have gone through all the vocab.
Demonstrate for the class: Get several Volunteers from different vocab groups (one from red, one from blue, etc) to come out the front, with their chairs. Say "Switch chairs, blue and green. Gesture to the students so that they stand up, then move them to the other chair. Do this a few times, just to make sure that they understand.