I have taught Arduino to over 100 local youth, adults and seniors through the Nelson Tech Club over the past four years. One of the most useful tools to explore this subject in educational contexts is plug-and-play sensor packs. These packs are worth the investment, many of the parts can be sourced individually. Small starter packs can be found for about $50 on many websites, and up to several thousand dollars for educators looking for a well-rounded inventory. Those who are inexperienced, but interested in Arduino can harness easy to follow plug-and-play logic and focus more on coding by utilizing interchangeable electrical circuit “bricks” to remove circuitry guesswork.
You can find great deals on Arduino components, as well as Beagleboard and Raspberry-Pi accessories at canada.newark.com.
The Nelson Tech Club has a large inventory of Arduino UNO micro controllers, sensor shields, network shields, motor shields, real time clocks and over twenty unique sensor bricks. Many of these types include: LEDS, buttons, servos, steppers, photovoltaic, thermal, magnetic, metallic, potentiometers, etc. There seems to be an endless variety to choose from, all of which are easy to incorporate into any project.
Arduino is a great compliment to any Hackerspace and I highly recommend sensor packs for any age to learn with. The NTC offers Arduino resources for Hackerspace members to explore with every week at out Public Wednesday Hackerspace.