Why 3×5 is and isn't 5×3

http://underscore.io/blog/posts/2015/11/17/why-3x5-is-and-isnt-5x3.html

by brainsmith • 11 years ago

2 4 11 years ago

underscore.io

merb• 11 years ago

this is so childish from the teacher.

5x3 == 3x5

Complexity is a major aspect in computing but not in school for undergraduates.

Also the kid should get a +1 since he used a law of math to reduce the complexity of the operation. That's more insane than proving this kid wrong.

FroshKiller• 11 years ago

You are confusing the equivalence of the result of the operations with the equivalence of the operations. The operations are not equivalent. That is the point. The question is not testing just whether you arrive at the correct result but whether you arrive at the correct result via the correct operation. The question clearly prompted the student to apply a particular strategy, and the student did not correctly apply that strategy. It's very cut and dry.

There is also a big difference between teaching a complex subject to a student and laying the groundwork for a later class. You can see that in the array problem on the same test. That's introducing matrices without getting into full pre-calculus yet.

astr0n0m3r• 11 years ago

The student very clearly applied the repeated addition strategy to solve it. It's very cut and dry.

noelwelsh• 11 years ago

The actions of the teacher are debatable but not really what the article is about.

Why 3×5 is and isn't 5×3

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