Reversing Fish

In my new book, How to Find a Rainbow, Reena and Rekha discover that you can only see a rainbow if the sun is shining behind you and it’s raining in front of you.

This ‘reversing fish’ makes use of some of the same science that explains how rainbows form!

You will need:

• A clear cylindrical glass or jar of water

• A piece of scrap card or paper

• Something to draw with

What to do:

Step 1: Draw a fish on your piece of paper about a third of the width of your glass.

Step 2: Lean your piece of card or paper against something so that it is upright.

Step 3: Put your glass of water up against the paper and slowly move it towards you until you can see the fish clearly and it is looking the opposite direction. 

Step 4: Now, if you move the glass to the side and back again, you should be able to see the fish looking one way (on the paper) and then the other (through the glass).  

Step 4: Try experimenting with other shapes or pictures!


We see things because either they give out light or they reflect light and that light enters our eyes. 

When we look at the fish drawn on the paper without the glass of water in the way, light from the surroundings reflects off the fish and into our eyes. 

When the glass of water is in the way, light reflecting off the fish bends (refracts) as it goes through the glass and water and then bends again as it comes out of the water and glass. 

When the glass of water is at just the right distance away from the fish, light reflecting from the right hand side of the fish is now on the left and light from the left hand side of the fish is on the right. This makes the fish look like it’s changed direction. 

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