?? English instruction:
• Take one of the wheels out of its slot and hold it in front of your face, so that
you are looking at its black back.
• Now look at the mirror through the uppermost slot with one eye. Spin the
wheel – slowly at first, then faster. First to the right, then to the left.
• What do you see on the disc?
• What do you see in the mirror when you look through the slots in the disc
while it is rotating?
• What happens when the rotation is very slow?
• What do you see when looking directly onto the rotating disc?