Circles: The best one is here, the students actually now sing this song every time that I even talk about circles. They love it. My neighbouring teachers may not like it as much.
This one I can't get to upload nto the page but it is worth clicking on. I even had a former student email me because they couldn't find this video and wanted the link. Her email was: I hate math but that song helped me remember.
Second best and was a favourite for a long time. The kids in my class used to actually sing this one without me even asking them. They loved the Pi is 3.14 approximately part for some reason.
Drawing the perfect circle: For some reason my students are just amazed by this and then want to try it.
From one of my favourite math blogs: http://mindfull.wordpress.com , she posted this animation that I have used a few times to demonstrate the area of a circle. The students can visually see why Area is 3.14 * radius squared.
and a second one
Fractions: It may be corny but a lot of my students remembered this and actually repeated it during a test.
Subtracting with New Math: The student in my class have been singing this all year and I have a group that memorized it:
I will post more soon and add to the list. Please help as well.