My school doesn't post grades on a daily basis. My kids' schools do.
I have a tough time believing that the teachers can't manage to contact the student, at least to tell them they're in trouble. .
I'm going to hazard a guess that, at some point, tests and quzzes were returned. I don't have a single student in any of my classes who doesn't have a decent idea of how he or she is doing in my class. They've gotten all their quizzes back, all their tests back, and I'll happily inform anyone who asks how many homeworks they owe.
But the reality is that I simply do NOT have the time to inform the parents of each of my students how they're doing. We have progress reports twice a year, and report cards three times a year. I have close to 180 students. I cannot call every parent after every test, after every quiz, after every missed homework.
I will respond to any parent who emails to ask how their son or daughter is doing. But I have had parents ask that I let them know every two weeks or something-- I always reply that I'll be happy to respond to their emails. I give them my testing calendar and let them know that they can expect a graded test within 48 hours of each of those test dates. But I will not promise to let a parent know each time a child fails a test, or goes below an A or whatever.
We're nearing the end of a marking period. About 2 weeks ago, I got in touch with the guidance counselor of any of my seniors who were in jeopardy of failing. The guidance counselors then pulled the kids in and spoke to them. Some responded, some did not. But the effort was made, even if it didn't involve mom and dad.
If I taught 6 year olds, it would be different. But at this point, aside from the personal inconvenience to me, it's about a 16 or 17 year old taking responsibility for his/her own education.
OP, it's certainly possible that there was an error.
But if your daughter had fifteen 80's, a 68 and a zero--
and they all were weighted the same-- her average would be a 74.59
Lets say, though that she had 3 tests: 80, 68, and 0, and 14 homeworks, all of which earned an 80. And that her test average was weighted equally with her homework average. That would give her a test average of 49, a homework average of 80, and an overall average of 65-- failing in her school.
Let's say test grades of 68 and 0, and a homework average of 85. If they're weighted evenly, she has a 60.
It's entirely possible that that zero was on a test or something that was weighted more heavily than, say 10 or 15 homeworks. That could certainly legitimately pull her below 70.
My question would be why she got a zero. And it would be directed at my daughter, not her teacher.