http://argyll.epsb.ca
http://www.shodor.org
http://people.hofstra.edu/
http://regentsprep.org
http://mathforum.org
http://nlvm.usu.edu
http://nlvm.usu.edu/
http://www.learner.org
Links for students to practice:
An extensive unit for independent learners
Unit 3 Parallel Lines
Lesson to discover properties of parallel lines