make a real rainbow st patricks day science experiment

make a real rainbow st patricks day science experiment

Most of us don’t fully understand what makes a rainbow. But in today’s St. Patrick’s Day Science experiment, we will make one and show how a piece of God’s glory can be explained in science.

St. Patrick’s Day Science Experiment: Make a Real Rainbow


– Plastic box

– Sheet of white paper

– Mirror

– Water


Every time we see a rainbow we know that nature is at work. But as Christians, we get to believe the whole truth: that God is at work and we can appreciate it through science. Let’s make our own rainbow to remind us on St. Patrick’s Day that God’s rainbows are one clue to us about God’s nature.


1. Fill a plastic box with water and place it near a sunny window.

2. If the wall next to the window isn’t white, place a sheet of white paper next to the window.

3. Place a mirror inside the box of water facing the window.

4. Tilt the mirror towards the sunlight. A rainbow will be reflected on the wall or sheet of white paper.


Ordinary white light, like that from the sun, is made up of many different colors all of which have a different wavelength. Normally, when we see light from the sun, it appears colorless. However, Isaac Newton discovered in 1666 that when he passed regular sunlight through a prism (basically, a triangular piece of glass), the prism would split the light up into a band of colors.

The band of colors is called the spectrum which appears in the order of red, orange, yellow, green, blue, indigo, and violet.

When it rains, the air is filled with raindrops. These raindrops act like a prism. If sunlight passes through the raindrops at the proper angle it is split into its spectrum, which is made up of the colors of the rainbow.


A rainbow is a little like the Trinity. The Trinity is one God. But it’s made up of the Father, Son and Holy Spirit. Light from the sun looks like just one light. But when we add a prism, we can see the different parts. Let’s remember that God, the Father, Son, and Holy Spirit, bring lots of colorful experiences to our life, and they’re always with us, even when all we see is clear light!


If you liked this St. Patrick’s Day Science experiment, you will love our “Rainbow in a Glass” Science Experiment!  Do you have other St. Patrick’s Day activities that your kids really enjoy?  Share them below!  And be sure to Become a Fan on Facebook and Follow Us on Twitter!