If you want to vary the game a bit, you can introduce new rules. For example, if a student says two pieces of vocab instead of one (e.g. "14, 15" or "March, April") then the direction reverses and they pass the bomb back to the person that just gave it to them. Another rule could be that if they say three pieces of vocab (e.g. "14, 15, 16" or "March, April, May") the bomb skips a person in the same direction.