Correct the errors in the following paragraph.
The fifty-star American flag was designed by a highschool
student named Robert G. Heft for a school project. Heft
originally recieved a B- from his teacher Stanley Pratt. Pratt
agreed that if the flag design was accepted by the US
congress he would reconsider the grade. According to Heft
his teacher honored there agreement, and changed his grade
to a A for his project after his design was chose and adopted
by Presidential proclamation in 1959.