Have a webcam and a smoke detector? If you do you can make a clever alpha particle visualizer. An alpha particle is an ionizing form of radiation that is made up of two protons and two neutrons. It’s powerful but doesn’t penetrate very far, paper or your skin is enough to stop them. Inside smoke detectors is a tiny chunk of americium that produces alpha particles when it decays. If you place some of this near the CCD of a web cam you can see flashes of white light as the particle strikes the capacitors and over charges them. Over time this could destroy the device, as radiation can do to space craft or robots that work near harsh radioactive sources, but in this case it makes for a good practical visualization of radiation. This would make for a fine science fair project.