Rebuilt, I am not surprised you had trouble getting them to pay attention. Science, technology and math doesn't even appeal to the average adult, let alone the average child. I was not very interested even as I started high school, I was only interested in girls and band. Kids sometimes get curious for a few minutes but I doubt the best teacher in the world could utilize it for more than a few minutes at a time. Maybe it could last an entire class period if you had them doing organized experiments for credit, building balsa gliders or something with their hands. Late in high school the parental expectation factor affects those who are college bound, but I do not think eighth graders are going to care very much. Next time try and get them to do basic physics stuff like showing how heating air makes it expand, how magnetism works, how gravity can power simple machines, etc.