Make sure the children know the difference between a source of light and a reflector by showing them the following experiment.

Cut a small hole in the top of a black box. Ask them if they think it will be light or dark in the box. Place a torch in the box and ask the same question. Then place tin foil in the box. Will it be light or dark now?

Repeat with glow stickers, light bulbs, reflector strips etc.

They will see the difference between a reflector, that needs light to glow, and a source of light, that will shine by itself.