  We have currently designed and partially implemented three collaborative  activities.  The first one was based on the <A HREF="http://www.cs.washington.edu/research/metip">Mathematics Experiences Through Image Processing (METIP)</A> <A HREF="http://www.cs.washington.edu/research/metip/warper.html">Image  Warper</A>.  The interface looks very similar, but students can cooperatively  interact with a line by each selecting an endpoint and moving them  simultaneously.   <P>
