A very simple and inexpensive black light can be easily configured from a "Clamp Lamp" from the hardware store and an inexpensive UV light from the reptile section of a pet shop.
Your students can use the black light module to examine samples to phosphor containing compounds such as detergents, eye drops, tonic water and nontoxic fluorescent dyes from a highlighting pen soaked in distilled water. If your students stir a container of very cold distilled water with fluorescent highlighter, then pour the cold liquid into a beaker or warm distilled water under the inexpensive black light unit shown in this illustration, they will see very clearly the principle behind a thermocline, or the action of warm and cold liquids and the heat energy moving through the liquids through convection currents. I call this simple demonstration a Neon Spiral and ask kids to predict what they will see beforehand in a simple sketch and explanation for their science notes.
The "Clamp Lamps" are very inexpensive, simple to assemble and use, suitably durable for lab experiments and easy to store as well. I like to keep them in all of my science classrooms and use them often when my students are studying the behavior light rays and nature of light energy.
Do you have any recommended science experiments using inexpensive materials? Did you find these ones useful? Let us know what you think.