One of the things I really like to do in a lesson is to play music which is related to the topic. Sometimes they are straight-forward, but not always. Some kids figure out what I'm doing quite early on, and then it becomes part of the lesson for them to guess what the topic is, or how the song is related to it.
Chain reaction (the Diana Ross version of course) for anything to do with Radioactivity.
The Vegetable song (Beach boys) for Digestion
Good morning starshine (from the musical Hair) for Life cycle of stars
A New England (Kirsty MacColl) for Satellites
However, in a much crueller way, I also like to play 'science songs' which get inside students heads and hopefully helps them remember the ideas. Most of these are from 1950s or 60s recordings which can be found at 'Singing Science Records' . They are very dated, but I love them. At a previous school I included 'E-lec-tric-ity' in the department lesson plans, and you could hear students coming out of their science lessons singing this song. Great!
Other classics of the genre:
The photosynthesis song by Peter Weatherall
Meet the elements by They Might Be Giants
The elements by Tom Lehrer
Bunsen Burner song by John Otway
Electric Car by They Might Be Giants
Digestion Blues by Joe Crone