Light follows laws, so you can learn how light will behave.
1.    One law of light is that light always travels in a straight line. Light also moves extremely fast: 300,000 kilometer per second. Light that starts at the Sun takes 8.5 minutes to travel down to Earth where people can see it. Light from the other nearest stars takes more than four years to reach the Earth because those stars are so far away.
2.    It can be deflected upon passing from one medium to another (refraction). Bending pencil experiment.

Clear air doesn't bend light at all.
3.    White light can be split into different colors. Experiment with prism.

White light consists of all of the colors we are able to see. When light passes through a prism the light bends. As a result, the different colors that make up white light become separated. This happens because each color bends at a different angle.
Activity. Now let’s conduct an experiment with the "Newton disk".

Thread a toothpick through the hole in the middle of the circle. Put the toothpick with a sharp end on the table. Try rotating the circle at first quickly, and then slowly.
Visible white light consists of a mixture of seven primary colours. If you mix them, you get a white colour. If you mix the three primary colours, you get all the other colors.

The task. Draw a constellation by connecting the dots. What is this constellation?

(2;7), (2;12), (8;14), (11;13), (12;5), (6;1), (10;10), (11;10).

Home assignment. Try to "create" a rainbow. Pour water into a flat container. Put the mirror in it so that one part of the mirror should be under the water, while another part must be above it. The back of the mirror should be directed to the inner wall of the container. Direct the beam of a flashlight to different parts of the mirror so that reflected light falls on a white sheet of paper.
Take a transparent glass jar, fill it with water and light it with a flashlight - you will see a rainbow where the beam comes out. If you don’t manage to do it, don’t get upset"