My jaw sometimes locks when i chew, or try to open my mouth too wide. i'm still in school and healthy besides this. is it normal?

Normal: This is a common problem. Your temporomandibular joint is the hinge that connects your lower jaw to your skull. As we grow, this join frequently becomes lax and can get "stuck". Try eating slowly and only fully extending your jaw when necessary, you should grow out of this problem with time.

Normal, no: But not uncommon. You may have displacement of the disc in your jaw joint. Please see your Dentist. Sometimes, but not always, treatment such as thermal application, biofeedback, exercises, night guard, orthodontic treatment, occlusal adjustment, etc. may be required. Between now and the time you're examined by your Dentist, try not to open too wide, soft diet, warm compresses.

TMJ "Closed lock": One of the common consequences of the anterior TMJ disc displacement is the "closed lock" without reduction. Early treatment is fairly quick and uneventful. See an orthodontist or TMJ specialist for a conservative evaluation and treatment.