This instructable is based on a kids science project that I am doing in a few days time with my daughter and a few of her friends. It's simple and fairly quick to do so although it does involve some soldering I don't expect that we will have trouble doing this with our small group of carefully supervised 7-year-olds.
The idea for this project was inspired by this article over at Evil Mad Scientist although the circuit is modified to be a little more efficient. Because it's made up from a simple set of parts it would make an ideal beginner's electronics kit. I'm therefore putting this forward into the "kit" challenge as well as the education comp'.
This kit could be used for an introduction to science and electronics from ages of about 7 upwards. It requires some simple through-hole soldering and employs batteries and a solar pannel, which might be at the level of a young junior school child. However, it also uses a diode, which is a slightly more sophisticated concept, both NPN and PNP transistors and so could be the basis of an introduction to transistors and it uses a blocking oscillator in the "Joule Thief" part of the circuit which could be used to illustrate inductance at a higher level again.
There are many learning points at different levels from this kit:
At the lowest age group (say 6-9 years) I'm using this as an introduction to the concept of circuits, to soldering and to very basic components (see final step). I'm not formally a teacher but I have been running young kids science projects for a few years now and they tend to be well received.
At a somewhat older age (say 10-14), this could be an introduction to discrete semiconductors - to diodes and transistors. Towards the top of this group one might discuss NPN vs PNP transistors at least from a functional point of view.
At an advanced stage (sat 15+), this could be used to illustrate advanced electronic concepts such as inductance and the correlation between electric and magnetic fields. A more theoretical consideration of semiconductor doping and the function of diodes, LEDs and NPN vs PNP transistors would also be suitable. The LED and low Vf diode in fact allow discussion of band gaps and some quantum mechanics if appropriate.
This is a nice, sustainable-energy kit, with all the power for the lamp being sourced from renewable solar energy. It uses scavenged jam-jars as the enclosure but could also use some scavenged parts such as toroids from old CFLs
This is a small simple and low-priced kit with a wide range of learning points. It's green, it looks cute and works at the end of it!
Edit March 2013:
I've been working with Joshua Zimmerman over at browndoggadgets.com to make these little boards available through his site. Leave a message if you're interested, or pop over there and see if he has them up yet.