Build a rainbow density tower with just water plus one special ingredient…salt! (Or, swap salt with sugar to make a sugar density rainbow!) Learn how to do this colorful classroom science experiment below 👇 What you need: Salt Water Food coloring Measuring cup Teaspoon 5 plastic cups 1 tall, narrow glass (we used a graduated cylinder) Pipette How to build a rainbow in a glass: 1. Start with ½ cup of five different colors of water: red, orange, yellow, green, and blue. 2. Add ½ tsp of salt to the orange, 1 tsp of salt to the yellow, 1 ½ tsp salt to the green, and 2 tsp salt to the blue. Make sure to add no salt to the red. 3. Add the blue water to your container. We used a graduated cylinder and added 5 mL of each color. 4. Using a pipette, gradually add the green water, then yellow, orange, and red. What’s going on? Salt makes water more dense, and it will stay at the bottom of the container because the less dense (because it’s less salty) water wants to float on top. By adding the...