Earlier this week I gave Julia Toews, the Head of BASIS Tucson, an opportunity to write a post on The Range stating her views about her school. Mainly, she was responding to a post I wrote which maintained that BASIS has a highly selective student body.

I found Toews' argument that BASIS does not have a select student body to be unconvincing. However, I understand why she tried so hard to defend the school against the "selectivity" charge. If, as she claims, BASIS truly had a representative student body which included students from across the academic spectrum, that would mean its high test scores and Top Ten ranking in U.S. News & World Report would be truly exceptional, that BASIS had figured out a remarkably successful method of educating students. However, if its student body is made up of some of the top students in the area, that would mean it is just one of many schools across the country — district schools, charter schools and private schools — that offers a rigorous, challenging education to high achieving students. If the latter is true, and I believe it is, that means BASIS' students should not be used as an example of a charter school succeeding where district schools fail.

Toews presents some facts and figures to "prove" BASIS Tucson represents an academic cross section of Tucson area students. One bit of data she doesn't mention, however, is the students' AIMS scores. They provide an interesting look at the academic achievement of students entering BASIS. More on that later in the post, including a request that Ms. Toews supply some information I don't have access to.

Toews begins by dispelling what she calls "a myth that we serve only middle and upper income students." She’s right, I’m sure, that BASIS has lower income students. I’ve never thought differently. She isn’t able to calculate that number by counting students on Free or Reduced Lunch, because BASIS Tucson doesn’t offer free or reduced lunch. Using other indicators, however, she leaves the impression that upwards to a third of the students are from lower income families.

For the sake of argument, let’s accept her estimate. That has no bearing on whether the school is academically selective. Look at TUSD’s University High School (UHS), for example. It requires an entrance exam for admission, meaning it is academically selective by definition. About 30% of UHS students qualify for Free or Reduced Lunch. Toews didn't offer figures for the ethnic makeup of her student body, but for the sake of completeness, here are the stats for UHS: 51 percent Anglo, 31 percent Hispanic, 11 percent Asian American and 3 percent African American. The UHS data makes it clear that a school can have an academically select group of students with high achievement scores and top national rankings and still be reasonably diverse in terms of its students' economic status and ethnicity.

Toews argues that BASIS Tucson doesn't have a selective student body because it is "an open-enrollment, tuition-free public charter school that is forbidden by Arizona law to be selective in our admissions." She's right about the school's enrollment process, but there are lots of ways to create an academically select student body even if you have to take all applicants or hold a lottery if too many people apply. We could argue endlessly, and fruitlessly, about whether BASIS uses alternative selection processes. Instead, I want to look at a way we can use data to determine the academic makeup of the students who enter BASIS.

Clearly, household income of individual students doesn't tell us much about their educational achievement levels. The University High stats put that issue to rest. But there's another measure we can use. If we knew students' AIMS scores from the year prior to their entering BASIS, we would have a reasonable idea of the academic ability levels they carry with them when they walk into the school. Much as I think the AIMS test is misused and overused, it nevertheless provides a reasonable, approximate snapshot of students' reading and math skills, especially when applied to a group of students rather than individuals.

The earliest grade at BASIS Tucson is 5th grade, so if we had the average 4th grade AIMS scores for the incoming 5th graders, we would have an idea of what kind of academic skills they bring in when they enter the school. Unfortunately, I have no way of tracking down the scores of 4th graders who came to BASIS from a variety of schools. So the best I can do is look at the AIMS test BASIS students take in the Spring of their 5th grade year and see if we can figure backward to what their 4th grade scores might have been. It’s an imperfect measure, but since I don't have the 4th grade scores at my disposal, it’s the best I can do.

So let’s look at those 5th grade scores, as well as scores for other 5th grade students in other schools.

In both 2012 and 2013, 99 percent of BASIS 5th graders passed the AIMS Reading test. In 2012, 93 percent passed the AIMS Math test. In 2013, 96 percent passed.

By way of comparison, statewide, 79 percent of Arizona's 5th graders passed the AIMS Reading test and 63 percent passed AIMS Math. The BASIS passing rate is 20 percent higher than the state average in reading and a 30 percent higher in math.

BASIS Tucson is next to the Catalina Foothills School District, which is one of the state's top achieving, and highest income, school districts. In 2013, every Cat Foothills school but one earned an "A" grade from the state, and the one exception earned a "B." In both 2012 and 2013, 96 percent of the district's 5th graders passed AIMS Reading and 85 percent passed AIMS Math. Even comparing BASIS Tucson with its high performing, high income neighbor, BASIS came out 3 points higher in reading and 8 to 11 points higher in math.

Looking at TUSD, 75 percent of the districts' 5th graders passed AIMS Reading and 54 percent passed AIMS Math. That makes the BASIS scores 24 to 40 percent higher than TUSD scores.

Even when we only look at TUSD schools with "A" and "B" state grades, about 88 percent of 5th graders passed AIMS Reading and 75 percent passed AIMS Math. That's still 10 to 20 points lower than the BASIS passing rates.

As I said earlier, I can't go back and look at the BASIS students' scores when they were in 4th grade, before they enrolled in BASIS. Instead, let's look at two possible theories explaining why BASIS' 5th grade passing rates on AIMS are so much higher anyone else's.

First is the "Huge leap" theory, which explains the high 5th grade scores this way: The 5th grade curriculum at BASIS is so rigorous and the teaching is so spectacular, even though students began the 5th grade at a similar level to students in the greater Tucson area, after 8 months of instruction, they were able to make a huge leap in their achievement, which meant that 10 percent, 20 percent, even 30 percent of those who would not have passed AIMS if they had attended another school passed at BASIS. Frankly, the "Huge leap" theory flies in the face of everything I know about student academic growth, based on my research in the field and my experiences as a teacher. It doesn't sound credible. I doubt it's true.

Second is the "High achievers from the start" theory, which explains the high 5th grade scores this way: The incoming BASIS 5th graders entered the school as high achievers, and their 5th grade AIMS scores were more a reflection of their previous achievement levels than the quality of education they received during their first 8 months at BASIS. The "High achievers from the start" theory makes far more sense to me.

I'm not satisfied leaving the two theories untested, especially knowing that the students' 4th grade AIMS scores would go a long way toward proving one of the two theories correct. That's why I'm asking Ms. Toews if she will go through her school data and give us the average AIMS scores of her 2012 and 2013 5th grade students when they were in the 4th grade. I'm reasonably certain that information is in the transcripts BASIS Tucson receives when the students transfer into the school.

I agree with Ms. Toews that we should get beyond the question of selectivity and look at the curriculum and teaching strategies at BASIS to see what we can learn from them. But you don't get beyond a question by ignoring it. Good education is about a systematic search for the best answers to questions we have. I would like to continue that search by employing all the information at our disposal to decide whether or not BASIS Tucson has an academically select student body.