Topic Selection Screen for an upcoming Q&A app

A concept mockup for Q&A app to be used by high school students. Employs fresh and clean visuals for a pleasing aesthetic. This screen shows the onboarding after the user logs in, where they are asked to select topics that interest them.

The visual metaphor: topics are branches on a tree, and questions/answers are leaves on the branch. The number of leaves and their freshness on the branch (green/orange/none) denotes the volume and recency of activity within that topic. The user can nurture their tree by asking questions or rating answers within a topic, which adds leaves to the branch.

Check out the attachment to see what the browsing topics screen looks like!