Illuminations is a project designed by the NCTM (National Council of Teachers of Mathematics. It includes interactive tools for students and instructional support for teachers.
Desmos is the next generation of the graphing calculator. The calculator can instantly plot any equation, from lines and parabolas up through derivatives and Fourier series. Data tables open up a world of curve-fitting and modeling. Sliders make it a breeze to demonstrate function transformations.
Geogebra lets you explore algebra and geometry, much like it’s proprietary cousin, Geometer’s Sketchpad. Geogebra requires Java to run, and can either run in a web browser with no download, or you can install it to your computer using the offline installer.
Wired Math provides games, lessons and challenges for grade 7 -10 ( and could be used for enrichment in grades 4-6)
Download a handout with 25 ‘math magic tricks’.