NeoK12 offers a set of YouTube videos explaining and illustrating magnets, electromagnets and magnetism.  All videos and lessons on this site have been reviewed by K-12 teachers and are safe for kids.

Power-hungry Dr. Volt is trying to shut down the city by taking over its power supply. Can you foil him? Learn basic electricity facts, learn about circuits, build some circuits, and conduct some circuit experiments.

Teachers, you can access individual modules without the game environment: electricity in our lives, simple circuits, building circuits, circuit experiments.

The Blobz Guide to Electric Circuits interactive game is an introduction to electric circuits for kids. Sections include: How Circuits Work, Conductors and Insulators, All About Switches, Changing Circuits, and Circuit Diagrams.

Each section includes a lesson, an activity, and a brief quiz. When a student scores 4 or better on the quiz in each section, they earn a printable certificate.  Up to 5 students at a time can participate in one game.

The game is ad-free and a really good introduction to circuits for elementary school students.

From site:  Welcome to the OhmZone!  Here you can build any kind of circuit you want.  In the bottom right-hand corner of the screen, you have a battery, some light bulbs and resistors, two switches, and wires to connect everything together.

You can measure voltage using the voltmeter and current using the ammeter.  Just place them over the part of the circuit you want to measure.