The students standing at the front of the line have to watch your movements carefully as you stand in front of them and quickly point to a part of your body, this could be anything from your feet, hands, ears, mouth, nose, elbow, fingers, teeth, hair, shoulders, knees etc.
The first student to correctly say the name of the body part can sit back down at their desk while the other student must return to the back of their respective line.
Continue this process until one of the teams has everyone sitting back down at their desk, they are the winners!
Make sure the other waiting students remain quiet to keep the game fair, give them only one guess each and feel free to play more than one round to give the losing team a chance to improve.
You can even introduce a points system where the winning team gets an amount of points equal to the number of students left in the other team's line