Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]

https://files.eric.ed.gov/fulltext/ED572414.pdf

by jethkl • 4 years ago

4 15 4 years ago

files.eric.ed.gov

jethkl5• 4 years ago

In 1978, a US-based study posed this question to 20,000 8th graders. Just 24% selected the correct answer. This is basically equivalent a random guess. In 2014, the same question was posed to 48 suburban US students. Only 27% selected the correct answer.

HarryHirsch• 4 years ago

That outcome also explains why the avocado toast propaganda worked. Propaganda isn't telling falsehood, it's omitting truth, math in this case.

wruza• 4 years ago

The answer is so obvious that it isn’t even worth testing or commening on.

Did you guess correct one, btw?

jethkl5• 4 years ago

I agree that this is a trivial question. But the linked pdf explains why it is an interesting question: it was posed to 20k US 8th graders in 1978, and the results were random. The same question was posed to 48 US students in 2014, and results were again random.

tgflynn5• 4 years ago

It seems like it's testing two very different things. If you choose the third or fourth answer it means you don't understand fractions at all. If you choose answer one it means that you either tried to do the exact calculation and made a mistake or else that you don't have much experience with approximate arithmetic, which really shouldn't be surprising since very little emphasis is placed on that in school.

1970-01-01• 4 years ago

Much worse is the example showing their inability to eliminate answers when multiplying decimals.

jethkl5• 4 years ago

Yes. I interpret the results as evidence of serious and systemic problems.

tgflynn5• 4 years ago

I'd say there's a big difference between someone choosing one of the first two answers versus the last two.

jethkl5• 4 years ago

Perhaps. However, if there were any evidence of 1-or-2 versus 19-or-21 type thinking, I would expect the results to be non-random. But the results of asking students who should know the answer were equivalent to random guesses.

tgflynn5• 4 years ago

Where in the paper is the distribution of answers over the four possible choices discussed ? The fact that the number of correct answers is close to what you would expect if the students were guessing randomly does not imply that the actual distribution of responses was uniform.

EDIT: In addition the conditions under which this test were given could matter a lot. How much time did the students have to answer ? Did they have access to scratch paper or did they have to do everything in their heads ? If they only had 5 seconds to answer I wouldn't find a random distribution of responses all that surprising.

Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]

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