You should be able to see all the words you have learned and group them
I feel there should be a way, on the homepage, to see all the words you have learned. In this feature you could group all the words by their function ie all the nouns together or all the verbs together etc. I've started again from scratch so I could write notes as I do the lessons and this type of feature would be so helpful to me.
There's the Vocabulary section with stuff grouped by skill, and quite a lot of them are by function. This is unfortunately not always the case, as in the Basics sections.. I guess that's the closest you're going to get for the time being.