How many datasets should I use throughout my course?
One dataset per chapter is typical. Some courses use a single dataset throughout. In this case, it has to be a reasonably rich and interesting dataset to keep student's attention over the whole course. A few courses use multiple datasets in each chapter, but you have to be careful in this case that you don't spend all the time introducing datasets instead of teaching other concepts.
If in doubt, choose
1 business or finance dataset
1 science or social science dataset
1 entertainment or sports dataset
1 personal dataset (something related to your hobbies, or to your home town or country)