Robert Grant writes:
This web page is something I constructed recently. You might find it useful for making artificial datasets that demonstrate a particular point for students. At any rate, if you have any feedback on it I’d be interested to hear it. I’ve tried to keep it as simple as possible but in due course, I’d like to add more descriptive stats, an optional third variable and maybe an option to make one categorical. It might also be interesting to get students to use it themselves to construct ‘pathological’ datasets where the stats would lead them astray, to help them understand how to spot problems and the importance of diagnostic plotting.