M.M.
Maybe the test was taken at an earlier date when he wasn't sure or not too comfortable with the teacher yet. My first daughter in preschool did this. She was so shy but I explained to her that she can trust her teacher because her teacher was there to help her learn. She did great so maybe just make sure you keep working with him at home for self confidence and let him know that the teachers are there to help him learn. Hope everything works out good luck!!!