“Home Button” where you can find “suggested” posts based on the posts that you upvoted.
Posts you have seen are slightly more transparent, that way you can quickly tell if you have already seen them and focus on new posts. Plus, ability to filter out seen posts in “Home”.
Ability to filter posts by categories such as mathematics, literature, history, personal life, ... and create custom filters with keywords. Use a “2-level” filter. First category is more general like “science” and a second filter for topics such as “math”, “Physics”, and more specific subjects within the category.
Add a section for articles, so that user can engage in political, philosophical discussions and ask questions. For articles intended for learning, add a “questions” section and the ability to filter questions by “unanswered”. (That way you can make sure to clarify the questions of everyone for a given topic.)