This has been my discovery of the week. I take no credit for it - I found it tucked in the back of The Teacher's Toolkit as a tool to help develop teamwork in a class.
I've used it for lower ability year 11 boys to get them working together, for twitchy year 9s who need to stop and do something else in the middle of the lesson and for year 10 who were about to go off to their science mock exams. They've all loved it. Give it a try.
You need to split your class into two teams, boys versus girls worked well.... Each group then has to decide which character they are going to be, a wizard, a giant or a dwarf - I found cartoon images of these and projected them up on the board, along with the rules. (From here on in it's a lot like "Rock, paper, scissors")
Wizards beat giants by casting spells
Giants beat dwarfs by stamping on the ground
Dwarfs beat wizards by tickling their feet.
I mimed these for the class to demonstrate....
On your count ("1......2.......3.......") everyone in the team has to do the action that goes with the character their team has chosen - wizards put their hands out in front of them and wiggle their fingers, giants put their arms above their head and dwarfs crouch down.
The suggestion is that a team gets two points for a win and one for a draw, and the first to 10 points is the winner. I've been doing "best of three" as an end of lesson thing.
Oh, and you get to giggle along with every kid in your class as they pretend to be wizards....