Predictions do not always prove true. Many of the things that we think will complete a circuit by conducting electricity, fail to do so when tested. On the other hand, some of the items we think of as insulators (blockers of the flow of electricity), do indeed conduct electricity. While our experiments with
random materials and a D-cell battery are safe and controlled, working with other forms of electricity would be more dangerous. Students now know that electricity "travels" through materials, and in doing so, it may be a danger to someone in contact with those materials.