This easy project can be used to teach many different topics. We make these fun xylophones when we are learning about colors. First the kids use measuring cups to fill the bottles with increasing amounts of water. Then they use eye droppers to drop food coloring or liquid watercolors into Snapple bottles. They learn that they can make the secondary colors by combining primary colors but that primary colors can’t be made by mixing colors together. Once they have created all the bottles, we give them a spoon and ask them to tap the bottles and see what happens. They quickly discover that each bottle makes a different noise. This is a good time to ask them why they think the bottles make different noises. The xylophone is made available in the classroom for independent exploration.