This site has searchable video cases of real elementary math lessons teaching standards based mathematics lessons. You can also see a complete lesson plan with handouts.
The NCTM website has excellent ideas for lesson plans, interactive on-line math activities, challenge problems, and more. NCTM offers many professional development resources such as journals, on-line conferences, information about regional conferences, an
This website lists a bunch of different interactive activities and is sorted by content standards, so if you are looking for a geometry activity you can click activity and a whole bunch will come up.
This link has many different videos and activities that work through many math topics. You can show only the parts you want, but it combines many ideas. The videos are not too long, maybe 10-15 minutes, to introduce topics.
This website has a list of math game activities. I like that this website is set up by grade, even though not all students may be at the same level, it is easier to find different activities that are level appropriate.
ide@s provides Wisconsin educators with teacher-reviewed, standards-aligned lessons, interactive tools, video, and other resources for use in curriculum development and classroom instruction.