I'm a little late for the party. The Star covered WaPo's Most Challenging High Schools list a week ago. But I was out of town, so now I'm making up for lost time.

The reason this is a big story locally is that three Tucson schools cracked the top ten, including two BASIS charters. BASIS Oro Valley is number one and BASIS Tucson North is number six. So what does the list mean? Here's a hint. The two BASIS campuses are both fairly new, as is BASIS Chandler, which came in number two. The more established BASIS campuses scored lower.

Before I get into the rather simple math (the list is created using a ridiculously simplistic equation), let me say I like the fact that this list calls the schools the most challenging, not the best. That's actually a reasonable description. BASIS and, I imagine, the other schools in the top 100 (University High is Number 37) make students work their asses off. They take lots of academically rigorous classes, and excellence is expected. Are they the best schools in the country? That's an impossible question to answer. What does "best" mean, and how do you measure it? But challenging? You bet they are, and students entering those schools should understand the academic challenges they'll face.
So, how are the rankings created? It's a very simple—too simple—formula: Take the total number of Advanced Placement tests (or International Baccalaureate or Advanced International Certificate of Education) given at the school and divide it by the number of graduating seniors. Here's how that looks as a mathematical equation:


To get the highest score, you need to maximize the number of students who take the tests (they don't have to pass them, just take them)—meaning you require lots of those nationally tested classes—and minimize the number of seniors.

Let's look at the BASIS Oro Valley, the top scorer on the national list with 20.44. It had a total of 206 high school students, and only 25 of them were seniors. Seniors made up one-eighth of the student body. Why so few? Oro Valley is almost brand new. This is only its second senior class. To get its 20.44 challenge score, its high school students would have taken a total of 511 AP exams, or 2.5 per student. That shouldn't be tough, since taking lots of AP classes is a requirement. Students even take one in the eighth grade.

If the school had just five more seniors, the Challenge Score would have been dropped from 20 to 17.


BASIS Chandler's score is right below the Oro Valley campus with 20.06. It had 28 seniors out of a high school population of 188. BASIS Tucson North, a few notches lower with 14.93, had 39 seniors out of a class of 250, meaning seniors made up more than one-sixth of the student body. That's why Tucson North scored lower than the other two. Is Tucson North less "challenging" than the Oro Valley and Chandler campuses? The answer is no. Their curriculum is identical. Tucson North just had a bit higher proportion of seniors.

And that explains why these three BASIS schools, all of which had their first senior class the previous year, scored in the top ten and the more established BASIS campuses didn't. The longer the school is around, the more seniors, and the more seniors, the lower the challenge score.

Like most of the quick-and-dirty lists we love so much, this one is simplistic and misleading. Most of the top 100 schools are probably more-or-less as challenging for students as those in the top 10, but their AP-test-to-senior class ratios aren't as advantageous as those at the top.

A Have-You-Heard-Of-This-Tucson-Charter? Note. Ever hear of Accelerated Elementary and Secondary charter school in Tucson? I hadn't, even though it made number five on WaPo's Most Challenging list. Maybe this is the reason it's flown under my radar. It has a grand total of 23 students in its high school, five of them seniors. But I guess those 23 students take a hell of a lot of AP classes, which makes it the fifth most challenging high school in the country.