I was thinking semicolons from the beginning, and, as it turned out, my reasoning was similar to yours. The only real background knowledge required is whether or not a student can identify a complete sentence. Percentages have numerous usage types, and the connection between types is not immediately apparent. Your point, however, about semicolons being used incorrectly most of the time was not something I had previously noticed, so nice work there. I liked your algorithm/thought process here!
The serial semicolon is now tested on the SAT, and I've seen students confused by that on the practice adaptive test (the first time it showed up) since we hadn't emphasized it.
I think of percentages as part of a group of math concepts --- percentages, proportions, and probabilities/stats -- that all share some characteristics, other than starting with "p." They are mostly middle school subjects and thus are forgotten math, and also, easy to learn . But, they also are all concepts that are readily embedded in question frameworks that make easy math hard to figure out. So, there may be two levels of teaching these things.
Good point – I've seen the serial comma on ACTs also (like D03 #21). It's true that it doesn't follow the rule, but luckily the rule it does follow is pretty easy to learn. I would argue it's quite a bit easier to explain than a similarly-frequent percent variant, like markup/discount.
I would push back a little on percents being easy to learn...for students who have never really understood equivalent fractions, percents are really hard to teach. A question like "75 is 30% of what number?" will stump them. Or at least that is what I've seen with my students. But I agree that these percent questions are then sometimes embedded in really challenging word problems and/or graphics which make it even harder for students to apply something they've memorized but not fully understood.
I was thinking semicolons from the beginning, and, as it turned out, my reasoning was similar to yours. The only real background knowledge required is whether or not a student can identify a complete sentence. Percentages have numerous usage types, and the connection between types is not immediately apparent. Your point, however, about semicolons being used incorrectly most of the time was not something I had previously noticed, so nice work there. I liked your algorithm/thought process here!
Interesting and helpful. I have a few comments.
The serial semicolon is now tested on the SAT, and I've seen students confused by that on the practice adaptive test (the first time it showed up) since we hadn't emphasized it.
I think of percentages as part of a group of math concepts --- percentages, proportions, and probabilities/stats -- that all share some characteristics, other than starting with "p." They are mostly middle school subjects and thus are forgotten math, and also, easy to learn . But, they also are all concepts that are readily embedded in question frameworks that make easy math hard to figure out. So, there may be two levels of teaching these things.
Good point – I've seen the serial comma on ACTs also (like D03 #21). It's true that it doesn't follow the rule, but luckily the rule it does follow is pretty easy to learn. I would argue it's quite a bit easier to explain than a similarly-frequent percent variant, like markup/discount.
I would push back a little on percents being easy to learn...for students who have never really understood equivalent fractions, percents are really hard to teach. A question like "75 is 30% of what number?" will stump them. Or at least that is what I've seen with my students. But I agree that these percent questions are then sometimes embedded in really challenging word problems and/or graphics which make it even harder for students to apply something they've memorized but not fully understood.