I posted my Whiteboard Challenge #4 to voicethread.com here @ http://tr.im/o32.
I had fun working this one out and thinking of ways to use voicethread with my students. I like the option of either adding voice recording or txt response. This is another outlet of collaboration in a larger scale. I plan to use this resource to further challenge my Math Club students. I am going set up a few additional activities using voicethread and I will blog on the results of its integration.