Home-made rainbow Separate light into its spectrum. Leave a small hole in the blinds for a beam of light. Put the bowl on a table, with the mirror under water so that the light reflects upwards. You should have made your very own mini rainbow on your wall. In Vain Use this sentence to remember the colours of the spectrum - red, orange, yellow, green, blue, indigo and violet.
Some humans can only see up to blue.
If you want to measure the height of a building, climbing it with a tape measure is a bad idea. A better way is to use shadows to measure heights. Find a time when the length of your shadow is the same as your height. At this time, the length of the building's shadow will be the same as its height, so all you have to do is measure the shadow. Clock Work Make yourself into a human sundial.