PNAS study finds double-dose algebra instruction among peers boosts college attendance and completion

July 18, 2021

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A long-term review of students who received extra algebra help in 9th grade improved educational outcomes later in life

By Sarah Steimer

Ninth grade students who scored just below eighth grade math benchmarks and took an algebra support class — in addition to a regular algebra class — were more likely to stay in and complete college, compared to those who did not take the double-dose algebra class.

But a long-term study published in the Proceedings of the National Academy of Sciences found there are several variables required for such positive results. For starters, the improved rates were seen among students who performed somewhat below the median math score, versus those who scored very low. And the benefits of the double-dose class were also most pronounced in schools that kept students in support classes of peers of similar skill levels, compared with schools that combined students with minor and major algebra learning needs into the same support classes.

Stephen Raudenbush
Stephen Raudenbush


The research — from the University of Chicago’s Stephen Raudenbush and Jake J. Smith, along with St. Louis University’s Takako Nomi — has followed Chicago Public School (CPS) students since 2003.

Raudenbush, the Lewis-Sebring Distinguished Service Professor in the Department of Sociology, says the double-dose strategy was initiated after an unsuccessful 1997 attempt to make algebra available for all ninth graders. The effort was part of a nationwide push to equal the playing field so more kids had a chance to go to college. But not all students were prepared to take algebra at the time it was offered.

Assigning kids to the double-dose class based on the eighth grade math benchmark created a regression discontinuity design for the study, which helped the researchers determine the causal effects of interventions.

“The idea is that we can look at people who are just on one side or the other of the cut-off point, and assume those people are very similar, almost as if it's randomly assigned,” Raudenbush says.

A paper published in 2016 looked at the short-term effects of the double-dose classes, finding a positive effect on test scores, course-taking and passing courses. The latest paper reviewed the long-term effects, showing the percentage of students from this cohort who earned a college degree rose from 12% to 17%, and those who earned a four-year degree rose from 6% to 10%.

Raudenbush says there’s no clear reason why the positive effect was only seen in students who took the supporting algebra class with others who scored similarly in eighth grade, but the team outlined possible explanations. The most plausible reason has to do with how teachers set their goals for instruction.

“There's a long line of research that suggests that secondary math teachers use whole-class instruction, meaning they teach pretty much everybody at the same pace,” Raudenbush says. “Teachers tend to pitch the pace and level of the instruction to the middle or maybe slightly below the middle of the class’ skill level. So if you're a teacher and you're assigned to a very low-skill class, then you're likely to peg the conceptual level and pace of instruction lower than if you had a higher-skill class on average.”

That means median-skill students in a class with lower-skilled students are likely to have less opportunity to learn algebra than if they were with peers at their own level.

Whatever the reason, Raudenbush outlined three main takeaways from the study’s long-term findings. The first is that it shows a path to success for low-income students who are highly underrepresented in the STEM fields. The second argues against the idea that interventions need to happen early to be effective.

“There's been a big debate about whether interventions on cognitive skills like math that late in life would have much of an effect,” Raudenbush says. “There's been some pessimism in the academic literature about that, and an argument that you have to start early. This is showing that you can make a real difference by increasing instruction time as late as ninth grade in kids who are 14, 15 years old.”

The third big takeaway is that these interventions needn’t be expensive. Adding a supporting class to boost outcomes requires a rearrangement of the schedule, versus reorganizing the curriculum, adding summer instruction, offering tutoring, or changing class sizes.

According to Raudenbush, the research emphasizes the need to optimize instruction for all levels. He and other researchers are also looking at ways to improve educational opportunities for the lowest-skilled students, for example. Experts suspect a tactic like double-dose algebra is not enough, and that a more intensive intervention is required for this cohort. And Raudenbush again emphasizes the need for taking a life-course perspective, versus early intervention only.

“You've got to think about how to do things that really work for kids early and then how to build on those successes with interventions later on in life,” he says. “Think cumulatively, because inequality results from a variety of forces over the life course that robs kids of opportunity.”