As a student/foreign language learner, I want to show/hide keywords or explanations from my written notes, so that I could review and recite the keywords/explanations.

As a UI designer, I want to hide/reveal annotations, so that I could a) differentiate the annotating remark from the wireframe / structured notes and b) present notes (to myself and others) with clarity.

I believe note-reviewing is an essential part of the note-taking experience, I try to be more proactive to learn through my notes. Some alternative apps I used are margin notes 3, and liquid text. Margin note 3 in particular, has a emphasize feature, which allows users to hide/reveal the emphasized word for memorization. Both apps, however, are not handwritten-notes-friendly.