It's said that a butterfly flapping its wings can change the course of a hurricane halfway across the globe. The idea behind that is that lots of small causes can add up to big effects. On the other hand, one great big cause-such as that same hurricane-can have many different effects, depending on what you are measuring. Weather, economics, politics, even traffic, these are complicated systems, and your students should have a foundation for thinking about them.
The following charts offer many options for charting causes and effects, whether single into multiple, multiple into single, parallel, or other configurations.