So 7th grade as you already know have been learning about potential and kinetic energy so I found this video, well song, very repetitive, but it got the point across. I played it (where they could only hear the music but not see the video) for several days as the students were walking in.
It was a great discussion starter for the lesson. I would start asking questions about what the song was about and of course they weren't listening, so then I would have to play the song several more times to help facilitate discussion. (Sneaky aren't I!)
Some students starting complaining that they couldn't get the song out their heads and many were caught humming it in class (YES!! Gotcha!). Then one girl complained that she felt like she was in jail, because she was being held hostage, being made to listen to the song over and over again. Really!!
OK OK, so here's the video.