06 Mar 2017: Fixed a bug on page 5 where the x tool didn’t work.
16 May 2016: Updated websketch page 8 to eliminate tracing, which was confusing.
31 Oct 2015: Updated this page to the website format.
This web site is based in part upon work supported by the National Science Foundation under NCSU IUSE award 1712280 (July 2017 through June 2019) and KCP Technologies DRK-12 award ID 0918733 (September 2009 through August 2013). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.