Wolfram Demonstrations is a website created by Mathematica where you can get thousands of Demonstrations. Demonstrations, just like GeoGebra applets, are interactive visualization of concept. The site contains more than 8000 Demonstrations in science and mathematics and in other fields such as Business and Social Systems, Systems Models and Methods, Engineering Technology, Creative Arts and more. The Demonstrations can be downloaded for free and can be embedded in blogs and websites.
I highly recommend that you view the interactive version below of the demonstrations on Odd Number Theorem and Newton’s Rotating Bucket Experiment. To view the demonstrations, download and install the free Computational Document Format (CDF) Player.
The Odd Number Theorem
Newton’s Rotating Bucket Problem