From this site you can select E-examples and Illuminations which provide a multitude of interactive classroom activities, resources, and links to exemplary lessons which support the philosophy of the Principles and Standards for School Mathematics. (
http://standards.nctm.org/info/about.htm
)
Select a grade level and math topic and you will be directed to a site with objectives, "Standards" match, and an online video clip. (
http://www.pbs.org/teachersource/index.htm
)