This free graphic calculator can also serve as a Scientific Calculator, has graphing capabilities, offers a unit converter, and can create a table of functions from values entered. It also has a set of references for formulas.
"CCL4s provides an interface for entering observation data as well as access to all the Content Standards for Mathematics K-12 and the ISTE NETS.S. The collected observation data can be shared via email or with our unique built-in instant meeting. The graphs are very interactive and allow observers to merge different observations to compare and contrast different teachers or the same teacher over time. Using the Timeline feature, observers can track the observed Look-fors through time."