• Iron Lynx@lemmy.world
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    1 year ago

    Nah, the kid’s right. Suppose Marty eats 4/6 of his pizza p1, and Luis eats 5/6 of his pizza p2, it means that for 4/6 p1 > 5/6 p2, p1 > (5/6)/(4/6) p2, which equals p1 > 5/4 p2

    In other words, Marty’s pizza needs to be at least 25% larger than Luis’.

    • Double_A@kbin.social
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      1 year ago

      Exactly! The answer the kid gave is the “correct” one because it shows a proper reasoning about fractions. While the teachers logic assumes that fractions are some kind of absolute value of measure???

    • Strae@lemmy.world
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      1 year ago

      This is one of those problems that makes more sense with context. The teacher had the students working on “reasonableness”, which is essentially “does the question I’m asking make sense?”. The students were probably instructed to ignore actually trying to solve the problem when presented with one, but instead explain why the question either does or doesn’t make sense.

      In this case the student potentially misunderstood the task. The failure on the teacher’s part is wording the question in such a way that it actually has a reasonable solution, and isn’t necessarily an unreasonable question.

      • SoupOfTheDay@kbin.social
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        1 year ago

        This isn’t testing reasonableness. This is testing to see if a student understands that to properly compare fractions the wholes have to start as equivalent.

        Source: I use questions similar to this every year because if I don’t get some real funky diagrams.

        • NightDice@feddit.de
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          1 year ago

          But… you can totally compare fractions without the whole being equivalent. You just have to know the size of the wholes. It’s just a poorly phrased question that has more than one correct answer when only one was intended.

    • SoupOfTheDay@kbin.social
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      1 year ago

      It’s a pretty common problem in 4th/5th grade. I wouldn’t say it’s common core. It’s just making sure students know that to properly compare fractions the wholes need to begin as the same size.