Giving a presentation on electronics. Any suggestions?

My team coach recently asked me to prepare a 1-2 hour presentation on electronics. I know how they work but what are some good activities that 20-25 can do in order to learn electronics. Bear in mind that it has to be very cheap to do and we have very limited resources. Thank you for your help.

The University of Colorado at Boulder has a nice collection of simulations that you may find helpful.

Do you have a budget for this presentation? Should it be for robot electronics only or general discussions?