I think this is an old staple of elementary school lessons.
At the begining of the game the ALT is the wolf and the students are sheep. The ALT is on one side of the room and the students on the other. The JTE or HRT helps guide the students. They start by shouting 'Mister Wolf Mister Wolf How are you?' and the ALT answers 'I'm happy'. The students repeat 'I'm happy' with happy gestures.
Then the students step one or two steps closer to the ALT. Then repeat the above process. It keeps going the same way saying different feelings until the ALT answers 'I'm hungry'. At that time the students must freeze and the HRT either rolls a die or decides a number. The students can then retreat back that number of steps and freeze again. Then roll two dice or decide a bigger number and the ALT can make that many steps towards the students. If the ALT is close enough to a student he can tag them. That student is now a wolf and joins the ALT on his side of the room.
The other students go back and start again. This time now the ALT and the wolf student can tag students when 'I'm hungry' is called.
Play for a few rounds and then once there are a lot of wolves maybe restart the game from the beginning with just the ALT as a wolf again.
The classic variation on this activity has the students run to safety when 'I'm hungry' is called but this gets a bit too wild and dangerous and frankly its hard to catch anyone unless they want to be caught.