Set/group selection activity
What I would like to see is a set selection task. This can be approximated with matching tasks or drag and drop exercises but this usually requires revealing to the learner the nature of the set/category. What I envisage can be seen in the mocked up screenshots. I'm not competent to do the programming but I am guessing most of the relevant routines already exist. What I would do is detect whether items overlap and, if they do, they are deemed to form a group. On submission the groups are checked to see if they are correct.