In reviewing websites linked to the Common Core, I came across this Math Reference Website http://www.mathopenref.com/index.html   that appears to be a pretty rich resource, especially for those who teach Geometry. The interactive “try this” modules that are located on the definition pages are great visual enhancements to the written explanations. Here is the review off of the Graphite website:

“Math Open Reference is a free interactive math reference covering high-school geometry, functions, and calculus. Five organizing topics cover plane, coordinate, and solid geometry, plus trigonometry and calculus. Four function explorers and a general online scientific calculator arm kids with awesome tools that really help them visualize what all these numbers and formulas actually mean.

Most entries open with a definition, follow with concise explanations of relevant concepts, then end with links to other relevant topics. Embedded “Try This” activities invite kids to interact with dynamic diagrams by moving intersecting points, lines, or vertices and watching the results. Sections within entries do not follow a formula but are appropriate to the topic: for central angle theorem, it’s simply “Exception.” About 40 entries are actually constructions: step by step animations showing kids exactly how to find the “center of a circle using any right-handed object,” for example.”

Here are their topics aligned to the Common Core: http://www.mathopenref.com/common-core.html

One warning- the ads are pretty distracting on this page and might even seem like part of the website. Warn your students to stay in the middle of the page and ignore what is happening on the sides.

How you can use this? Display on your projector and/or Smartboard when explaining an idea. You can also post a link on your eBoard or classroom website as a homework resource for your students.