I would agree that an evaluation would be very helpful.  In the interim you may want to write down when your child is able to pay attention and when he is not able to pay attention.  Some children are more distractable when there is alot of visual things around them or alot of noise.  A good book to read to help you see if your child is over responding to his environment or if he is ADHD is Sensational Kids by Lucy Jane Miller O.T.R. which can be bought on line or at your local book store and for free at your library.

I would first talk to his teacher and see if you can get more information as to how he acts in school.  Does he have a hard time sitting still?  Does he seem to get frustrated easily?  Does he have a hard time concentrating on one thing for a certain period of time?

I would then take this information and go to his pediatrician - they can give you a questionnairre for you to fill out, then one for the teacher to fill out, etc.  With this - they can determine if he has ADHD.  My daughter had a lot of the same problems you described - she ended up being diagnosed with ADHD.  Once we realized this and were able to help her - it was like night and day - her grades shot up and she started liking school.

well, I think you should like give him a good influence ...like if theres another child in school that could help him or tell him whats going on in the classroom maybe that would help or maybe the teacher could give him extra set of notes or a syllebus or something to help him out.

make learning fun for him :)) use colorful materials or worksheets. And never get tired of thinking and experimenting other motivations that can get his attention.

Keep the routine predictable and simple. One possibility includes a five-minute warning that study time is approaching, bringing your child’s current activity to an end, clearing the study table, emptying the backpack of books and supplies, and then beginning. It is best to learn how to do it, because then it will just buying an essay.