Here is another great site to add to your list of places students can find free photos for projects.
Kozzi earns revenue for the advertisements placed on its page. This allows them to provide their professional photo images free. I stumbled upon this site today and found it to be an incredibly rich resource for finding pictures. Using a simple copy/paste was much easier than downloading the images from the lightbox.
http://lessonsonamericanpresidents.com/ seems to have some great lessons on presidents! Worth checking out!
Mouth Power (http://www.mouthpower.org) can be done individually by students in a lab, but would be better on an interactive board as a class. Users take a trip through a lab to learn about dental hygiene and work through activities to earn teeth for their smile. The activity goes beyond the basics of telling students to brush and shows how to brush and the correct way to floss. It also has a neat time lapse feature to show what happens when you don't take care of your teeth.Cons: There isn't voice audio on everything, so non-readers will need assistance.
Check out http://blogush.edublogs.org/2012/01/24/20/, an insipirational blog post from Paul Bogush about giving students 20% of their time for free learning and exploration. I may consider doing something like this next year!
