My previous post focused on the main weakness of the 100-point scale which is the imprecision with which it is defined. Is it percentage of material mastered? Homework percentage completion? Total points earned? It might be all of these things, or none of them, depending on the details of one person's grade book.
Individual departments or schools might try to define uniformity in grading policies, give common final assessments, or spread grading of final exams amongst all teachers to ensure fairness. This might make it easier to compare two students across a course, but still does not clearly define what the grade means. What, however, does it signify that a student in an AP course has an 80 while a student in a regular section of the same course has a 90?
Part of the answer here is based in curriculum. Understanding what students are learning and in what order defines what is being learned, and would add some needed information to compare the AP and regular students just mentioned. The other part is assessment: a well crafted assessment policy based in learning objectives and communicated to a student helps with understanding his or her progress during the school year. I hope it goes without saying that these two components must be present for a teacher to be able to craft and communicate a measure of the student's learning that students, teachers, parents, and administrators can understand.
At this point, I think the elementary teachers have the right idea. I've been in two different school systems now that use a 1 - 4 scale for different skills, with clear descriptors that signify the meaning of each level. Together with detailed written comments, these can paint a picture of what knowledge, skills, and understanding a student has developed during a block of the school year. These levels might describe the understanding of grade level benchmarks using labels such as limited, basic, good, and thorough understanding. These might classify a student using the state of their progress with terms like novice/beginner/intermediate/advanced. The point is that these descriptors are attached to a student and ideally are assigned after reviewing the learning that the student has done over a period of time. I grant that the language can be vague, but this also demands that a teacher must put time into understanding the criteria at his or her school in order to assign grades to a particular student.
When it comes to the 100 point scale, it's all too easy to avoid this deliberate process. I can report assignments as a series of total point values, and then report a student's grade as a percentage of the total using grade book software. Why is a student failing? He didn't earn enough points. How can he do better? Earn more points. How can he do that? Bonus assignments, improving test scores, or by developing better work habits. The ease of generating grades cheapens the deliberate process that may (or may not) have been involved in generating them. Some of the imprecision of the meaning of this grade comes, ironically, from an assumption that the precision of a numerical grade makes it a better indicator. It actually requires more on the part of the teacher to define components of the grade clearly using numerical indicators, and defining these in a way that avoids unintended consequences requires a lot of work to get right.
Numerical grades inform a student's progress, but don't tell the whole story. The A-B-C-D-F grading system hasn't been in use in any of the schools where I've taught, but it escapes some of the baggage of the numerical grade in that it requires that the school report somehow what each letter grade represents. An A might be mapped from a 90-100% average in the class, or 85-100 depending on the school. As with a verbal description, there needs to be some deliberate conversation and communication about the meaning of those grades, and this process opens the door for descriptors for what grades might represent. Numerical grades on the 100 point scale lack this specificity because grades on this scale can be generated with nothing more than a calculation. That isn't to say that a teacher can't put in the time to make that calculation meaningful, but it does mean it's easy to give the impression of precision that isn't there.
Compounding the challenge of its imprecision is the reality that we use this scale for many purposes. Honor roll or merit roll are often based in having a minimum average over courses taken in a given semester. Students on probation, often measured by having a grade below a cut-off score, might not be able to participate in sports or activities. Students with a given GPA have automatic admission to some universities.
I'm not proposing breaking away from grading, and I don't think the 100 point scale is going away. I want to hack the 100 point scale to do a better job of what it is supposed to do. While technology makes it easier to generate a grade than it used to be, I believe it also provides opportunity to do some things that weren't feasible for a teacher to do in the past. We can improve the process of generating the grade to be a measure of learning, and in communicating that measure to all stakeholders.
Some ideas on this have been brewing as I've started grading finals and packing for the end of the year. Summer is a great time to reflect on what we do, isn't it?