How are rainbows formed?

Year 1, 2 and 3 learnt how rainbows are formed. We first came up with all of our ideas, we even learnt about Leprechauns. Then we watched a video finding out the scientific side of it and then added to our bubble diagram. We then conducted a few experiments. One with a CD, torch and water. We first tried shining the light on the CD without water to see what would show up. Then we added water to a bowl and submerged the CD into it to see if it would make a difference. The only change we saw was the shape of the rainbow that reflected went from a diamond shape to a star shape. We then coloured both ends of the tissue paper with the colours of the rainbow and placed both sides into water to see if the water would absorb and the colours would merge. We found out that the type of paper made a big difference to the absorption of the water. So the colours didnt merge but instead they spread into the water.