Reddit reviews Amazing Leonardo da Vinci Inventions: You Can Build Yourself (Build It Yourself)

If you mean near the anode of the battery between the two humps of wire, I don't think so. Looks like the reflection on the hump whizzing by the camera real fast. However, in an inductive load like a motor, if not handled, you can expect to see sparks when the circuit is broken.

See:

• http://www.artisancontrols.com/UtilityImages/ProductSupportPdf/16.pdf
  
  
• http://en.wikipedia.org/wiki/Flyback_diode
  
  As for material for your son, I have a couple things I always recommend to people when they ask. (I volunteered at a local science museum where I live. Got this question a lot.)
  
  An accessible medium is video. There are many, many fantastic shows around for kids interested in science:
  
  
• Magic School Bus
  
• Bill Nye the Science Guy
  
• Beakman's World
  
• Mr. Wizard's World
  
• Cosmos - Which just started up anew!
  
• NOVA
  
• Newton's Apple
  
  Most of those can be found on YouTube!
  
  Then there are more books than you could possible imagine. Even just on Amazon's top selling lists! Here are some that I remember growing up with (maybe I'm biased towards electromagnetism as a studying electrical engineer):
  
  
• You Can with Beakman
  
• Engineering for Every Kid
  
• Leonardo da Vinci Do it Yourself
  
• Make: Electronics (Which is fantastic for electronics!)
  
  And, just because I'm on a roll here, I'm subscribed to a bunch of channels on YouTube centred on science:
  
  
• ASAP Science
  
• Engineer Guy
  
• It's Okay to be Smart
  
• Minute Earth
  
• Minute Physics
  
• Numberphile
  
• Periodic Videos
  
• SciShow
  
• Sixty Symbols
  
• Smarter Every Day
  
• Veritasium
  
  Anyway, hopefully you'll have some fun with your son and maybe even learn something.