Need help with art class..

So for my art class all my projects have to be based on an idea/concept. We have to turn in a sheet with our idea/concept with 20 words that relate and also a subject matter with anothe 20 words. For example, a concept could be "freedom" and the subject matter could be "nature".


I'm having trouble thinking of concepts and ideas, and I don't have a clue on any other different subjects.

Some ideas I've thought of so far:

Growing up/becoming an adult
Friendship
Courage
Adventure