Decide how many groups need to be made with the number of students. If there are 20 students and a teacher needs groups of four, then there are easily five groups. Next, get a deck of cards. Choose all of the aces, kings, queens, jacks, tens and nines. Now shuffle the cards. Give every student one card. Tell the students with aces to meet, the students with kings to meet, the students with queens to meet, etc.
A similar tip is to take 20 index cards. Place a red star on four cards, a green star on four cards, gold star on four cards, a purple star on four cards, and a blue star on four cards. Then pass out the cards. This grouping method can be done with different types of candy, suckers, shapes, etc.