Bible Science Rainbow science experiment

The rainbows associated with St. Patrick’s Day often have a pot of gold at the other end. They are signs of hope. Biblically, rainbows are signs of hope and God’s promises. This rainbow, created with a glass and a flashlight, can help student’s understand one of God’s scientific wonders.

Bible Science Experiment Materials:

  • A clear, large drinking glass
  • Small mirror that will fit into the glass
  • Water
  • Flashlight
  • A room with white or light colored walls, or a large piece of white
  • poster paper

Bible Science Experiment Instructions:

1. Place the mirror in the glass and position it so it stays angled at the bottom, facing slightly upwards.

2. Fill the glass with water to completely cover the mirror.

3. Turn off all the lights and pull the shades down to make the room as dark as possible. If that can’t be done, do experiment in hallway with hallway lights temporarily turned off.

4. Turn the flashlight on and direct it to the mirror in the glass.

5. If you don’t have walls that are white or light colored, place white poster board behind the glass to see the rainbow.

6. If you are in a room with white walls, look around the room to find the rainbow. By moving the glass, the rainbow will appear in different places around the room.


When it rains and the sun comes out, the light from the sun hits the tiny water droplets in the air, causing the light to slow down and bend. The bending creates the arch of the rainbow. This is called refraction. Sunlight is made up of the seven colors of the rainbow. When refraction occurs through air moisture it causes those colors to separate so that you can see them individually. And that’s a rainbow!


Although the rainbow connection to St. Patrick’s Day has to do with leprechauns finding a pot of gold at the end of the rainbow, there is another more meaningful connection in the Bible. Genesis 9:16 says, “When the bow is in the clouds, I will see it and remember the everlasting covenant between God and every living creature of all flesh that is on the earth.” That is our Lord’s promise which we should remember when rainbows appear. We have something better than a pot of gold at the end of our rainbows. Gold can be spent, and then, there’s nothing. We have heaven, which lasts for all eternity!

Do you think your students will enjoy this Bible science activity?  Share your thoughts or comments below!  And don’t forget to Follow Me on Twitter, where I will share more great Bible science ideas!