overboard?

I just spent about an hour composing an email to DS1's Spanish teacher. We got report cards today, he got an F in Spanish.

Needless to say, this came as a horrible shock to all of us. He was expecting a B, having started strong but hitting a very rough patch towards the end of the quarter. Still, we hadn't run the numbers, but we figured he must be doing OK since we didn't hear one word from the teacher the entire quarter. All of DS1's other teachers gave the kids, fresh-minted 6th graders struggling to adapt to middle school, lists of missing assignments and what-not before the end of the quarter. Nothing from the Spanish teacher, though, so we figured he was OK.

Along with the report card came the access codes for us to check his grades online. Yay, and it's about time. There are not a lot of grades in there (he only has Spanish two days a week.) Still, average test grade was 84. Average homework grade was only 56, because he missed an assignment back in August, but didn't know it. Participation grade was 100.

His final grade for the quarter was 56, and F. I don't see how that was calculated, unless the final grade was equal to the homework grade, in which case, why record tests and participation at all?

I asked the teacher to please explain how those scores add up to an F, because I'm just not seeing how it gets there. I hope it was just a mistake, because otherwise I'm going to have impose some consequence on DS1 for failing, even though the rest of the report card is brilliant and he's been working incredibly hard all year.

I suppose I shouldn't take this so hard, but the kid is horrified. He's never received such a bad grade on a report card, and if he had known about that missing assignment, he would have turned it in. Even with only half credit, it would've brought his homework score up to 72, and then there would've been no question of failing.

I don't want to get branded as one of those obnoxious, meddlesome parents, but I truly don't understand this grade and I don't want to punish my son unfairly. I'm hoping I get a reasonable response from the teacher, because the last thing I need is bad blood at the school where I work and all three of my children attend.