How to word this teacher email? Urgent!?

I took an exam today for one of my cles. My school uses an online system that lets you monitor your grades. The teacher posted the grade online and it was very low. I am uming it is a typo. By the way, the test was one of those "scan-tron" things. (fill in the bubbles) I want to send her an email, asking her to check my grade again. How can I word it without sounding rude or self centered. I don't want to come off as being perfect and not accepting a low grade, nor do I want to insult the teacher. Can someone give me a specific email that I can fill in to send to her? Thanks so much for your help :-)