On Friday as a formal conclusion to our science unit on pushes and pulls students were given a challenge to design a way to move 5 rocks from the floor up to a table.  They worked in teams and had a variety of materials available for their use.  Pulleys were quite intriguing so most chose to incorporate a pulley into their design.  This was a great opportunity to practice team work and persistence and also lots of fun.  While we are officially done with the science unit I have had many requests to keep using the pulleys and other materials during choice time.