National Council of Teachers of Mathematics
Nctm: Illuminations: Proof Without Words: Pythagorean Theorem
Students use this computer applet to visualize the Pythagorean Theorem.
CK-12 Foundation
Ck 12: Interactive Middle School Math 8 for Ccss
A complete CCSS Grade 8 Mathematics course that includes interactives in every lesson, plus videos, hands-on activities, and questions with immediate feedback. Every lesson also has specifically chosen 'Related Modalities' that teach the...