During our small group investigation on how does light travels, we used a torch, a piece of string and cardboard with holes. We aligned the holes in the cardboard and shone the torch through them. We noticed that the light only passed through when the holes were in a straight line. When we moved the cardboard or the torch out of alignment the light was blocked. This showed us that light travels in a straight line. The string helped us visualise this straight path, confirming our observation.
