During the 1950's all sorts of crystal set kits became available, including some on the backs of cereal boxes. Now the hobby is coming of age again as those boys from the 50's have become fathers and want to pass on this radio magic. For this reason, a study of crystal sets is a great place to start to build a foundation in radio electronics. You also can learn about natural processes. The signals from distant stations will ebb and flow, particularly at night.
Crystal sets are a great tool for teaching, and they are a superb hobby.
Quaker Oats Box Radio summary and hints Our Quaker oats box radio project can be built in a few hours using a round Quaker oats box and parts that you can purchase from Radio Shack. A sharp junior high school student may be able to put the radio together all by herself, but grade schoolers will need adult help and supervision. The directions include soldering the parts together, which obviously needs to be done with adult supervision. If the child is in late grade school, have them hold the Oats box between their knees to hold it steady while they wrap the wire around it. It is fine to use lots of masking tape to hold the wires and parts in place.