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[quote=Anonymous][quote=Anonymous]"50% is "no credit earned," it's "see you next year," it's failing, that's the *zero* of the course grading scale"

Wrong.  A zero is the zero of the course grading scale.  The 50% rule does not prevent a teacher from assigning a zero for any student that did not meet the basic requirements of the assignment/assessment.[/quote]
Yes, but end of the day, the student is assigned a letter grade, at which point, how badly the student failed is irrelevant.  (But, yes, sometimes there are actual 0% grades, even with the 50% rule.)  Qualitatively, letter grades are a normal distribution with mean at C and tails at A and E--at least that was the original concept.

[quote=Anonymous]
"If a student earns 50% on every assessment, they will fail the class."

Also wrong, as that is not automatically the case.  For a start, homework is required to be graded for completion and is required to be 10% of the grade.  A student can fill out a homework assignment with gibberish and already have 10% of the course points.  I have also taught courses that have a grade distribution that has another category for project grades.  If the student does reasonably well on the project grades but earns less than 50% on all assessments, it is possible for such a student to pass the class.  In fact, I've seen it happen.
[/quote]
Sure, sure, but that 50% test average doesn't *help* them pass the class, it's just things could be worse.  If you want to analyze the situation, you can stop and look at the statistics of any part individually.  E.g. if the complaint is the 50% rule applied at the assessment level, focus on tests.

[quote=Anonymous]
"if there are no opportunities for extra credit to counterbalance, this does make it possible that badly failing a single test can do more harm to a grade than a perfect score can do good."

An incoherently-worded claim.  And one that is not really supported by statistics, given that outliers in *either* direction will skew the mean.
[/quote]
Ah, but when talking about grading, you're not dealing with a normal distribution, instead you're dealing with a *truncated* normal.  Here's an example (with a very high mean, but even if the mean closer to 75% truncation is typical):
[img]https://ai2-s2-public.s3.amazonaws.com/figures/2017-08-08/e8dacbce1f5b418b572656ac4f59e49f6129ce5f/42-Figure4.1-1.png[/img]
With a truncated normal, the situation is not symmetric, it's possible to get a a grade further bellow the mean than above the mean.  (And, again, I'm talking about the Platonic mean of a C, not the mean of a specific group of students.)  Without value judgement, truncation explains why a score bellow 50% is so painful.  E.g. If a student gets a grade of 25% and they want to get back to a 75% average, the quickest way to do it would be to score 100% on the next three tests, (1*(25%) + 3*(100%))/4 = 75%.  Likely a very difficult task for someone who just scored a 25%. The 50% rule is an example of a censored normal distribution. This is one way to remedy the situation, and reduce the impact of any one test.  It would then be possible to get back into passing range after one assessment, (50% + 100%)/2 = 75%.  Another possible remedy would be offering extra credit (eliminate the truncation by providing grading opportunities above 100%).  This isn't allowed in MCPS.[/quote]

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