I AM A KINDERGARTEN TEACHER FOR 6 YEARS
 YOU CAN TALK TO YOUR KIDS TEACHER FIRSTLY
BECAUSE IF TEACHER LIKES TO BE WITH KIDS KIDS LIKE TO BE IN THE CLASS MORE
THEN GIVE ANY PRICES IF YOUR CHILD LISTEN T YOU
WELL

Have you talked with his teacher and the school counselor?  Does he fail all tests or just tests in certain subjects?  It would be important to determine if he has a weakness in learning or if this is due to inattention.  His teacher or counselor should be able to help you determine if an evaluation of his academic skills is needed.  If it is mainly his inability to stay seated, you may want to try a "Sit and Move" cushion in his chair to see if he is able to stay seated longer.  The cushion can be purchased at www.Funandfunction.com

I think this is pretty common. My older son was like this at age five. He wasn't really ready for school, honestly. He did ok academically and we didn't hold him back but he just wasn't ready for kindergarten. If you can, you might think about pulling him out and waiting another year. My son concentrates better now but still struggles with it. We try to watch his sugar intake and give him Omega-3 supplements both of which seem to help.
Your son sounds normal, its just that there is a lot of variations of what is normal at this age.

TALK TO YOUR SON ABOUT THIS SITUATION EVERYDAY CALMLY,GIVE PRESENT IF HE LISTENS YOU AFTER 3 TIMES GIVE PUNISMENT IF HE DOESNOT LISTEN TO YOU