Explore in your own classroom cave to discover that objects can only be seen when illuminated. Students get their hands on play-dough and make stalactites, stalagmites, and bats to put in your classroom's cardboard box viewing cave. You will be surprised when you see how well Tedros test tube will illuminate your cave box when filled with water. Students will discover an innovative way to use sunlight. A water bottle full of light can be as bright as a light bulb.