With the Triple Venn Diagram Shape Sorter you can either set the rules or guess the rules by selecting the appropriate botton:
Try this applet which shows how a solid is formed from a net, just move the red slider from 0 to 100.
Using Algebra Trees form inputs, operations and output by dragging them onto the main workspace, connect them up and optionally connect to a graph. Click inside any of the elements to change the content.
Once you have tried a few of these applets you will find them intuitive to use.
Algebra Arrows for example could be used to compare different orders of operations. Build a tree, make the input x and note the output generated:
There are several applets which are excellent for showing plans and elevations, see for example Building Houses with side views where the user must construct a house given top, front and right views. Teachers familiar with the ‘Improving learning in Mathematics’ materials will recognise some of these applets.