Here you must mark the positions you think a ball is in.

The lasers are shooting beams of light when switched on. Then, they disappear and are replaced by an information about the interactions of the laser beam with the balls in the black box.

“There must be one there!” you think. These mark where you suspect a ball is placed in the black box.

At the end of the game, the right and wrong positions of the balls are also marked with "balls".

You can use them to mark some positions where you are sure there is no ball.