In summary, It would be hard for a six-year-old to learn much about electricity without adult guidance. A kit like this is available at a site like Bananarobotics.com.
#36
BiGyElLoWhAt
Gold Member
1,622
131
Perhaps something like this. I'm not sure if this would be considered a "snap" circuit, but what is talked about in this video by Steve Mould seems like it might be useful for younger ages.
You have a lot of good suggestions in the earlier posts. Do not worry about inductors, and capacitors. A six-year old is not (likely) ready for Ohm's law, impedance, phasors, and differential equations.
#38
mpresic3
448
323
Regarding touching a 9 volt battery to the tongue. This seems harmless and I did it hundreds of times, but when I got older, I used to listen to the radio with a rechargeable 9-volt battery. The instructions on the battery warned, do not carry in your pocket where coins can short the battery and produce burns. I never got burns but they did get uncomfortably warm. I would not want that on my tongue.