Stop for science is a site by Chandra X ray observatory. This site has tons of high quality content available for free.There is a set of beautifully illustrated posters on many scientific concepts including force and motion and when stars die. Poster are informative without being too detailed and the facts are explained with the help of pictures. They can be a good visual reference when studying one of these topics. There are many videos and animations on topics like Solar system, Photon emissions etc. Or you can download and print Chandra coloring and activity book, one of many printable content available, a 28-page coloring and activity book which includes general information on X-ray astronomy, Chandra and the STS-93 mission. It also looks at black holes, supernovas, galaxy clusters and more. Activities include mazes, word searches, connect-the-dots, crossword, code break, and word jumble. There are also presentations and powerpoints, screen savers and many other stuff so take some time and explore this site.