http://www.edheads.org/activities/simple-machines/

We began our science unit last week!  We started with physical science.  Our first topic is force and motion.  Within that topic, students learn about simple and compound machines.  This website is an excellent way for students to learn the difference between wheels and axles, pulleys, levers, wedges, screws, and inclined planes. It has real-life connections as well as conceptual diagrams with explanations.