About twins..

How many twins are in our school? I know five twins...yes I know five couples... We have lots of twins in our school, aren't we? Is it because our school is so big?
One couple is Kevin and Steven Duong as you guys know. Second one is Arabic twins whom I took ESL with. Third ... couple is the twins that I see during PE class (Yes..I am taking this class with bunch of Freshmen!!!!!!!!!!!) Fourth is Jake and his brother. And the fifth one is Peter and Matt who are taking Calculus AP. I got confused with them and I realized that they were twins... ... . Before that, I really believed they were a same person. And still I can't figure out who's who.