Visitors to this site can play different sounds to help understand concepts involving sound. Here are several quizzes you can take to help understand and remember concepts dealing with the periodic table of the elements. You can also take quizzes on many other areas at this site. This site has illustrations and interactive activities dealing with machines. This site has over 50 applets on different areas of physics.
Students can do labs online.
Two more applets are added to this site every month. This site gives good basic information on light and other forms of energy. Interactive quizzes are given after different areas to test understanding of the material.