I did a grammar project on past tense/present tense. Past tense is something that happened in the past, and present tense is something that is happening now, or a routine. Some ways of remembering them are that most of the time present tense is (action) -ing or (action) -s and most of the time past tense is (action) -an or (action) -am
How hard did you think think the topic was before you started it and how hard was really?