Click on the 'Need To Learn' tab just above the Reader frame to display Need-To-Learn view. This view of the Reader shows all characters and words that you've marked as need-to-learn. To mark a character or word as need-to-learn, use shortcut keys (Ctrl-B for characters; Ctrl-N for words) or the Need-to-learn checkboxes in each of the dictionary windows. When you encounter a character or word that is unusually difficult to remember or you just need to make sure that you study the entry, mark it as need-to-learn. Any such entries will appear in the Need To Learn view.