• Frezik@lemmy.blahaj.zone
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    15 hours ago

    That’s the sort of thing “new math” was trying to teach. Those sorts of breakdowns are exactly what the kids who were good at math were always doing, and teaching methods eventually caught up and realized they should just teach the tricks.

    Then a bunch of parents who were bad at math asked “new math? How can math change?” The fact that they even asked that question showed how their math education was lacking, but they seem to have won.

    • mic_check_one_two@lemmy.dbzer0.com
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      10 hours ago

      Exactly. Math has historically relied on rote memory for most mental math. Kids would have to fill out their times tables, addition tables, etc until they memorized them. I still remember getting pop quizzes in elementary school that looked like this:

      You only had two minutes to fill out the entire thing, which meant you only had 1.2 seconds per answer. You didn’t have time to actually calculate them. The point was that you were expected to have them memorized ahead of time instead of calculating each one.

      But rote memory is laughably bad at actually teaching concepts. You may know that 12x5 is 60, but you don’t have any understanding on why, or other ways to do that same calculation without rote memory. And rote memory is only decently reliable up to ~12x12. Anything past that, and it becomes too much info to track; kids simply start forgetting answers.

      The kids who were good at math (and I mean actually good at math, not just good at memorizing things) quickly devised methods to do this shit in our heads easily. Keeping track of multiple numbers in your head gets confusing. So “line them all up, add straight down, and carry 1’s” sort of falls apart if you’re doing it in your head. Especially if you’re trying to keep track of more than three or four numbers at a time.

      Essentially, 127+248+30 is the same as 105+250+50, but the latter is much easier to parse in your head. But yeah, the parents (who primarily relied on rote memory) didn’t understand why the new method would be more effective, because they didn’t understand the concepts surrounding the math.

      • boonhet@sopuli.xyz
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        10 hours ago

        I think it’s good to have a good set of these tables memorized and then based off those you can bounce your tricks. Eg if you know 5x12 by heart, you get 5x24 by intuition. Or even if you know 24/2 for that matter. I use simple examples but this could scale to less memorable numbers too.

        • blindsight@beehaw.org
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          9 hours ago

          It’s really helpful for quadratic factoring, too, since knowing at a glance that –56 is ±7 × ±8 keeps your working memory free to actually focus on the mathematical skills/concepts/problem.

      • yetAnotherUser@discuss.tchncs.de
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        8 hours ago

        Strongly disagree that memorization isn’t important. It’s THE foundation to be able to do effectively do more advanced stuff.

        Take the equation (5678 • 9876). Use long multiplication and you only rely on doing a bunch of single digit multiplications and additions. It’s so much faster to be able to instantly know each step instead of having to recalculate these “atomic” steps again and again in your head.

        You generally don’t need to be able to solve multiplications involving double digits in your head. It’s nice-to-have but otherwise useless, as long as you’re able to calculate the ballpark of the result.

        For example, (38•63) is roughly 2400 and I can then calculate it on paper instead of in my head.

        Head calculations are just so much more error-prone than written calculations. Don’t do them if you can avoid them. There’s a reason why math students (at a university) are infamous for being unable to make the simplest calculations in their head. It takes effort that could be spent somewhere else.

      • brygphilomena@lemmy.dbzer0.com
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        10 hours ago

        I only sort of agree. I still think that by forcing you to do that, by making you practice, makes the calculations “muscle memory” in that you aren’t memorizing the answers but can do the calculations faster and faster each time.

        Sure. Some people could memorize them. But others will learn to calculate quickly.

        • Bldck@beehaw.org
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          8 hours ago

          It frees you up to do more complicated arithmetic. Geometry would be too slow if you didn’t innately understand 3*60=180. Which you don’t get without 3*6=18

    • baldingpudenda@lemmy.world
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      14 hours ago

      I was trying to explain how and why they were teaching math to a family friend and they didn’t get it(multiplication stuff). I broke it down with pen and paper and they didn’t get it. Simpler example, nope. Eventually I had to explain how multiplication is just repetitive addition. They responded with WHAT! and I realized why they always wore open toed shoes. I sent them a link for 5th graders.

      • Mouselemming@sh.itjust.works
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        13 hours ago

        I’m not very good at math (but not an idiot like your example) and I wear flip-flops every day of the year but they’re not related.

        Are you trying to say something like “too dumb to tie shoelaces?”

        Because there are quite a lot of lace-up open toe shoes and sandals, as well as closed toe shoes without laces, so that doesn’t track.

    • dohpaz42@lemmy.world
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      14 hours ago

      As a parent who is bad at math, you’re not wrong. But given my kids are excelling in math (very high scores), I’ve learned to shut the fuck up about it and let the teachers do their black magic jobs.

      • Frezik@lemmy.blahaj.zone
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        9 hours ago

        I want to add that when I said they give away that their arguments demonstrate why math education needed to change, I do mean it. This is a clear cut case of the education system failing them.

        I’d normally be happy to throw snark at the idiot things parents say that make our education system worse, but not this time.

    • UnderpantsWeevil@lemmy.world
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      12 hours ago

      Those sorts of breakdowns are exactly what the kids who were good at math were always doing, and teaching methods eventually caught up and realized they should just teach the tricks.

      Well… kinda. “Getting to 10” was what New Math was trying to teach. So you’d take the 1 from 7 and give to 9, because 6 + 10 is easier than trying to finagle your way to 8x2.

      Then a bunch of parents who were bad at math asked “new math? How can math change?”

      You don’t have to be bad at math, strictly speaking. But there was a lot of brute memorization in traditional math. Times Tables, for instance, were something you just memorized straight up without thinking too deeply. Getting 16 out of 7+9 was something you just had to do on your fingers until you had it lodged in your head.

      Old Math tended to be slower and more tedious. New Math is more logical, but also somewhat counterintuitive until you get into the swing of it.

      The fact that they even asked that question showed how their math education was lacking, but they seem to have won.

      I’ve got friends with kids down in Houston. “New Math” appears to be alive and well, in no small part because it helps kids score higher on standardized tests.

    • limonade@jlai.lu
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      13 hours ago

      Never heard about new math. Where does this method comes from (geographically)?