Don Horrigan, a former priest turned public school educator, thought Prince George’s County was a splendid district for an experiment beginning in 1991, requiring all ninth-graders to take Algebra I and all 10th-graders to take geometry. The superintendent and school board were for it. Parents seemed excited.

But when Prince George’s became one of seven districts nationwide to pilot the College Board’s Equity 2000 program, many teachers in the district thought it was too much. Sure, they said, students could learn algebra and geometry eventually, but why so soon? They thought 42 percent of Prince George’s ninth-graders were taking remedial arithmetic because they weren’t ready for anything more.

“It is unwise to push a child — especially a slower-paced learner — who is not ready,” a Prince George’s high school math department chair told researchers Carolyn DeMeyer Harris and Jessica L. Turner. “I believe that when we push them we make them feel like failures when in actuality it was merely a timing issue.”

According to Harris and Turner, who worked for the Alexandria-based Human Resources Research Organization and wrote a report on Equity 2000, one Prince George’s teacher told a supervisor that the program was another loser. “We’re like little pigs at the trough waiting for you to throw more slop at us, and then we wait for it to go away,” the teacher said.

In my new book about Equity 2000, “The War Against Dummy Math,” I devote a chapter to the battle in Prince George’s. It explores clashing attitudes toward acceleration that are still with us and how very long it takes for student achievement to catch up with expectations.

Horrigan, a former science teacher and administrator, was the Equity 2000 coordinator for the county. He knew there was resistance but thought the program would solve a serious problem. The Maryland Functional Mathematics Test (MFMT), which required a grasp of sixth-grade arithmetic, was then the only state math test. Schools gave it so much emphasis that students who completed algebra at the end of eighth grade were not sent to geometry in the ninth grade, but took a prep course for the MFMT.

The superintendent asked: “What’s so hard about this?” He ordered an end to the MFMT class with little immediate effect. Horrigan agreed that better training for teachers meant more students could master algebra without more remedial math. But the high schools, Horrigan told me, “were set up in another way of thinking.” They had their own prerequisites for algebra, and the most important was the functional math class.

Horrigan and other district officials pushed hard. They had two-week teacher training sessions in the summer, Saturday academies for students during the school year and some of the best data on math progress of any of the seven pilot districts. By 1997, just 10 percent of ninth-graders were still in functional math. The portion of students earning passing grades in algebra climbed from 56 percent in 1991 to 74 percent in 1997.

Achievement as measured by standardized tests came more slowly. In 2005, just before Horrigan retired as principal of Parkdale High School, he noted that only 28 percent of his school’s students passed the state algebra test.

Parkdale’s passing rate on the state test was more than 60 percent this year. The district’s passing rate was 52 percent. This doesn’t match the passing rates in places like St. Mary’s County — 92 percent — but suggests the Equity 2000 people were right that more students taking algebra would eventually mean more students understanding it.

The argument these days is not about ninth grade but eighth grade, where more than half the students in many Washington area districts take algebra. Is that too soon? Ask me in two decades.