David continued to take his test.

He will frequently say his answer aloud and it will be correct in its oral form. Then, he will look at the teacher and try to gauge based on my reaction if his answer is correct. The answer that gets written on the page often has changes from the answer he gave aloud.
So, the answer that actually gets written on his page will often be different than what he said. These changes from oral to written cost him points.

Further independent study outside of class time may help build his confidence in his answers.