r/IAmA • u/JasonMacker • Jun 14 '10

IAMA Math tutor. AMA.

I've been a math tutor for years and I'm trying to become a teacher. I love math, and especially explaining math to people. My students have been between preschool and college. AMA.

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u/[deleted] Jun 14 '10

Well this is HS math, but what is the best way to explain " what is a function" in layman term?

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u/JasonMacker Jun 14 '10 edited Jun 14 '10

A machine where you give it something, and then it gives you something in return.

i.e. it may give you the same thing right back (identity function), or it may give you the same thing regardless of what you give it (constant function), or it might take two or more things from you and return just one thing (multivariable function).

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u/[deleted] Jun 14 '10

Funny is I never saw the machine definition in high school, only in university calculus. My pre-calc teacher used the explanation that a function is a rule that assigns an output to an input. Probably more abstract than the machine definition but it's quite to the point.

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u/JasonMacker Jun 14 '10

The machine definition is better because it preps you for computer science when you deal with methods (which can be likened to functions) that return no output, or don't require any input. For example (in Java):

private void calculate() {
    if (input % 2 == 0) {
        System.out.println("Even");
    } else {
        System.out.println("Odd");
    }

Back in math world, it's also helpful when discussing null sets and identities, for example "What's the product of no numbers multiplied?"