There is an underlying flaw in the current method you use. The categories :: Basic, Secondary, Intermediate is very subjective and depends on the point of view of the person. What is Basic for me, maybe very advanced for another person. Moreover the classification is also dependent on the subject being talked about – simple concepts in Botany may look very advanced for a mathematician. So let us think of another way to do things. Let us use subjects as the key. For instance, let us make activities on :: maths, botany, music etc. Will be easier for a new comer (learner or teacher) to quickly find the right spot.