http://projectsbyjen.com/ is a great website for online collaborative projects that Elementary school teachers can participate in.  It is easy to join and she takes care of all the organization.  The directions are explicit and my kids loved it!

We filled a plastic egg with jellybeans.  Then the kids rolled their eggs like a bowling ball down a ‘track’.  The kids then measured how far their egg rolled.  The results were added up and we found the average roll for our class.  This information was added to the google doc of other class averages for comparison.  There is even an Egg Fashion show, where students decorated their eggs in a creative theme.  I collaborated with the art teacher for that one