F-IF.7 Graphing

“Can’t graph it. Too big a line.”

“The line’s too big.” So what? Why does this matter to the student, and what does this reveal about his understanding of graphing?

2 replies on ““Can’t graph it. Too big a line.””

I may be WAY oversimplifying here, but my guess is that the student is so used to standard 1 to 1 scaling between the axes that this function simply won’t ‘fit’ into the graph s/he has envisioned.

I agree, this student does not understand scale in this instance. I would suggest that the student label the giant tic marks on the axes. This would give us a scale, and a clue that we need to change the window settings Also if they are using the calculator, and also using x for multiply as well as x for \it x they will be doomed. If this does not show up as an italic x, then by hand I use two c s back to back.
Why don’t we teach dot to elementary students, so they only have to learn one thing? I now use the asterisk as shown on TI83, because it’s easy to change the multiplication x into the asterisk. Then they get fed up of three (!) lines and put a dot because math is for the lazy (my math motto).

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