Interactive site showing the relationship between mass, force and acceleration: 

http://interactagram.com/physics/dynamics/NewtonsLaws2of3/ 

 

Birthday moon activity:

 

 Solar System Web Quest:

http://teach.fcps.net/trt8/SolarSystem/Planets.htm 

 

Science Class:

http://science-class.net/ 

 

For balancing chemical equations:

http://education.jlab.org/elementbalancing/