This site contains information and links to circuit challenges. A good tool for additional research for students or further exploration. This can also be a part of a WebQuest activity or simply used the challenge at the bottom of the page for part of a homework/classwork assignment.
A website which provides the terminology used in circuits but appropriate for students. This page in particular could become part of a scavenger hunt or WebQuest activity. It has some use as a stand alone resource as well.
These two are great for students struggling with simple circuits and can do a lot of different things, from using a volt and ammeter, like in class, to creating simple to complex circuits.