After my exams would it be ok if i reward my brain from all the hard work with a little weed. or would this just be bad for my brain.
Cannabis does not damage your brain once it is fully developed (at age 21 I assume). Go do some research. Myself, I have experimented with my academic results and smoking a lot. I came to the conclusion that it really depends on the person. In fact, after smoking a certain amount I feel that I am better equipped to study. Smoke when you feel you have to, study hard and everything will be dandy. Always use the herb to your advantage and not your disadvantage - and this application will be different for all people, because we all are different.
Smoking doesn't affect my ability to learn or anything, but I stop like a week before I have exams, and that's only because I get real lazy when I'm high and I can't be bothered to do anything. If that's not the case with you, smoke away. Why are you worried about smoking after your exams anyway?