a+b=c. Algebra can save a poor black kid’s life.

Doubling the amount of time poor kids in Chicago spent studying algebra in grade nine led to an 8 per cent increase in their high school graduation rate, and an 11 per cent increase in college enrolment.

That’s the finding of a terrific new paper out of the US National Bureau of Economic Research.

Given that US high school dropouts die earlier than graduates by 3-5 years and make up 7 out of 10 prisoners in the US, it is fair to argue that for thousands of these kids, algebra has saved their life.

The paper exploits a natural experiment whereby students in the Chicago Public School System were placed into double dose algebra classes (largely replacing music or art classes) if they scored below the national median on an eighth-grade math test. The researchers compare kids just above and below the cut-off. 


Barack Obama in Chicago in 1995. Photo By Mark Pokempner

The numbers of students in the algebra courses is substantial, because maths skills are thin on the ground in the 73 public high schools studied. In the US, just 20 per cent of hispanic students, 13 percent of black students, and 17 per cent of students poor enough to qualify for free lunches are rated proficient in maths. In the Chicago Public School System 90 percent of students are black or Hispanic.

“In the Chicago Public Schools (CPS), the focus of this study, roughly half of high school freshmen fail at least one course, with the highest failure rates in math courses”

Schools assigned weak students to a back-to-back lesson in Algebra with the regular algebra teacher, and gave the teachers professional development, permitting them to use different instruction methods, including working in small groups, solving problems verbally, and having students set problems for each other.


The impact on test scores was modest. But the impact on the students lives was not.

“…the test score impacts of this policy dramatically understate its long-run benefits as measured by educational attainment.”

The effect of double dosing in the first year of high school remained over time. Students who were in the program were 9.3 per cent more likely to pass algebra in that year. But they are also 7 per cent more likely to still be in school in the fourth and final year of high school.

The students who got the most out of the instruction were ones with poor reading skills. They end up passing three more subjects in high school on average, after taking the double dose, creating a 13 per cent increase in the number of poor readers who complete enough subjects to pass high school. The researchers suggest that the focus on using verbal methods to solve maths problems may explain this result.

Black students who got the double dose  also saw a dramatic effect, with a 15 per cent increase in college enrolment. For the double-dose population at large, the increase was 11 per cent. The effect can be seen in this chart:


For some of these student, the impact of these classes – which their 14 and 15 year old selves no doubt dreaded – will be dramatic over their life times.

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Thomas the Think Engine is the blog of a trained economist. It comes to you from Melbourne Australia.

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