Boy following me? whats up?

I just started my freshmen year at highschool. There is this boy who keeps hanging around me. Today, he asked me to sit by him in the back of cl, and now I am permenently seated their because today the teacher wrote down seating chart. Yesturday was his first "move" I should say, I was sitting at lunch and he just randomly comes up and sits next to me and starts asking me questions (first time we talked) Now he fallows me and just chats-it is a little distracting and hes not really my type..i cant really focus on my cl or have a nice lunch time with out it turning into an awkward situation. what is going on with him? I don't think Im pretty or anything and I have never seen him before. Any ideas of whats going on and how to get him to slack of a bit. One more thing, i also told the teacher i'd like to go back to my original seatin, she agreed but what am I going to tell him? what can I say so I dont hurt his feeling? I thought about "oh, I just cant see the board from the back row" ????? thx so much for helping me out-and write whatever you think, I wont be affended or anything but I need advice asap! thx!