I used the 3 Circle Venn Diagram Applet to make a diagram of food preferences in my family. I have one child who won't eat much in the way of meat or vegetables, and another who dislikes carbs.

You may well be familiar with Venn diagrams – the ubiquitous pictures of typically two or three intersecting circles, illustrating the relationships between two or three collections of things.

You can classify and compare shapes by using a Venn diagram. Each shape has been placed in the section of the Venn diagram it belongs in. Because the square doesn’t have any acute angles or a ...