At
Desmos, they believe in "learning by doing" and that everyone can learn and enjoy Math. Desmos is a FREE graphing calculator (the industry standard Texas Instruments
TI-83/4 costs about $100). Desmos can be accessed via the web or it can be downloaded from the
App Store onto an ipad or iphone or onto Google from the
Chrome Web Store. Desmos has
sliders that can be clicked on to see how graphs are affected by changes in the equation such as changing the slope or y-intercept of a line.