There are many sites on the internet with very good information about evolution.  Unfortunately there are also a number of sites that were written by non-scientists and do not reflect current scientific understanding of the topics.  Here are some links to useful activities and sites that contains scientifically accurate information:

http://evolution.berkeley.edu/evolibrary/article/evo_01.  A great resource that covers the whole of evolution in detail in a friendly and readable way:

http://www.nhm.ac.uk/nature-online/evolution/. The Natural History Museum website provides some good explanations for certain aspects of evolution with some nice images and informative answers to key questions.

http://www.wellcometreeoflife.org/interactive/.  A video by David Attenborough explaining the tree of life.

http://www.mnh.si.edu/mammals/index.htm.  Good site to enrich the learning of long term changes. Focus on mammals changes and adaptations.

http://www.newscientist.com/article/dn13620-evolution-24-myths-and-misconceptions.html#. This is a good article on misconceptions from the new scientist.

http://evolution.berkeley.edu/evolibrary/misconceptions_faq.php. This is also a good section on misconceptions from the Evolution 101 website.

http://www.sciencechannel.com/games-and-interactives/charles-darwin-game.htm.  This is a great game to develop an understanding about natural selection and evolution.

http://www.wellcometreeoflife.org/interactive/   An amazing interactive tree of life.  Fun homeworks could be set asking about time of divergence of common ancestors, and who is more closely related to whom using this site.