1. How do light waves travel? Get three index cards Punch a hole near the top, going through all three cards at once to make sure the holes line up later. Tape the cards to blocks or other small objects to make them stand upright. Set the three cards up in a row and shine a flashlight through them. O 0 What do you notice in the light when the hole in the cardboard is aligned? Now, move one of the cards slightly out of line. What happens?​