Subjects Addressed: Math K-12, Teacher Resources, Lesson Plans, Online Lessons in Pre-Algebra, Algebra, Geometry, others
Interdisciplinary: Yes
Site Search: Yes, at the middle of the page
Sample Activities At The Site: This site offers several types of math resources -- general, teacher, student, and parent. One of the neat features is the two-way, virtual whiteboard, a virtual chalkboard where students (and mentors at math.com) can draw their problem and reasonings so the other person can see their thinking.