The College Board will soon allow high school students to register for Advanced Placement (AP) exams in the fall, rather than having them wait until spring—just before the exams are held.

It’s a simple, seemingly inconsequential change, but in both the small- and large-scale studies the nonprofit conducted in U.S. schools, the option to register in the fall led to more underrepresented and low-income students taking the AP exams.

The idea came straight from educators. More than half of U.S. schools that offer AP courses have set test registration dates earlier than the College Board’s deadline, often months earlier, and they’ve observed positive changes in who signs up.

“The level of idealism with which [the schools] described benefits of this simple switch felt far-fetched to me,” said Trevor Packer, senior vice president of the AP Program, during a press briefing on Tuesday.

But the College Board, a 119-year-old organization that also oversees the SAT, decided to give it a closer look anyway. After a small pilot showed promising results, the group launched a larger, nationally representative pilot of 800 U.S. schools serving 180,000 students this school year to understand the effects of fall registration.

The results have astounded officials at the College Board, which in recent years has led several efforts to improve participation and performance rates among underrepresented students. Overall, student participation in AP exams increased 7.7 percent when the option to register in the fall was available (versus a 1.9 percent bump over the previous year for those who could register only in the spring). But among underserved minority and low-income students, the increase in participation was more dramatic.

Image credit: The College Board

The College Board is looking into a number of theories as to why this simple change, which will go into effect in the 2019-2020 academic year, has made such a profound difference. One leading hypothesis, Packer said, is that students don’t talk themselves out of taking the exam when they get to sign up that far in advance. Instead, they plan for it, they study and they persist. Registering in the fall also allows students more time to save up to pay for the exam in the spring, officials said.

The registration change was announced in the College Board’s annual report on AP program results, and it wasn’t the only update. Beginning Aug. 1, the organization will roll out its single-largest investment in the AP program, according to CEO David Coleman—a set of digital resources available for free to AP teachers to support them in planning lessons, creating assignments and providing personalized feedback to students.

Teachers will also be given the tools to build customized practice exams, including access to an online library with more than 15,000 real AP exam questions. The question bank is one of the most frequently requested resources by AP teachers, a spokesperson at the College Board tells EdSurge.

The impetus behind these new resources, Packer said, was to ensure that regardless of where kids go to school or who is teaching them, they have everything they need to study effectively and stay on track.

The class of 2018 set records for the AP program, with 1.24 million public school students taking 4.22 million AP exams. Those numbers have climbed over the last 10 years; last year, almost 40 percent of public school graduates in the U.S. took an AP exam, compared to 25 percent in 2008.