Why dont ctrl F work on macbook?

So i just recently went with a new macbook. On my last laptop when i had a question i was trying to find a answer to like in quizlet I could copy the question then inside of quizlet I could Control F and paste it and it would find it for me so I didn't have to scroll through the whole quizlet to find that one question and answer. Now with my macbook ctrl F does not work. Anyone know why?