This example facilitates the explanation of an optimization problem and offers a numerical solution that can later be solved analytically:
In this link, you can find a series of such problems.
“What’s my rule”
This applet is a game students can play in order to understand complex numbers. It comes from a series of applets whose goal is to improve students’ geometric understanding of the basic operations with complex numbers. The user tries to figure out a pre-defined rule relating one or two points to some other point:
In this link, you can see the full series.
Reconstructing the function from its derivative
This applet tests how well you can reconstruct the function from its derivative: