Here's a surprise: the ACT and SAT don't care about how much math you know.

That's an exaggeration, of course, but there's truth to it. In fact, a significant number of ACT and SAT math problems only partly test for math knowledge and math-specific skills. Instead, they really test for more general cognitive skills. Like attention to detail.

The problem below, taken from an official ACT practice test, illustrates this phenomenon well. Before reading on, take a look at it, and choose the answer that you think is best:

Did you choose (D)? If so, great!

If you didn't choose (D), then most likely you went with (C). If so, look closely between the sides of length "2" and "1", and you'll notice a small unlabeled side. This unlabeled side has a length of 1, so the perimeter is 13 + 1 = 14.

If you didn’t catch this subtlety, you’re probably thinking to yourself that the people who design these tests are evil, evil people. Well, you’re right ;).

But, we can take more from this exercise than just that. For one, it provides a window into the minds of the test-makers. What, exactly, are they testing with this problem? That high school students can find the perimeter of a shape? Hardly -- this problem appears as #51 (out of 60) on an ACT Math test where questions are ordered by increasing difficulty. Rather, problems such as these gauge attention to detail, the rigor with which students review their steps. So, the next time you work through an ACT or SAT Math problem – remember to double-check your work!

-Dani V, Instructor