President Joe Biden has met his goal of having most elementary and middle schools open for full, in-person learning in his first 100 days, according to new survey data, but the share of students choosing to return has continued to lag far behind.

The survey, conducted in March by the Education Department and released Thursday, found that 54% of public schools below high school were offering full-time classroom learning to any student who wanted it. It marks steady progress since January, when the figure was 46%.

But even with that milestone achieved, most students continued to learn at least partly away from school. Almost 4 in 10 students continued to take all their classes remotely, the survey found, and another 2 in 10 were split between classroom and remote learning.

The disparity reflects a trend that has alarmed education officials at all levels: Even when schools reopen, many families have opted to keep students at home for remote learning. It has been most pronounced among black, Hispanic and Asian American students, most of whom spent no time in a classroom in March, the survey found.

Education Secretary Miguel Cardona applauded the nation’s progress but also drew attention to racial disparities, saying schools must do more to reach all students.

“While we’ve made important progress, I will not be satisfied until 100% of schools are safely open for full time in-person learning for all students,” Cardona said in a statement. “The department will continue to work with students, families, educators, states and districts, to ensure our education system serves all students, not just some.”

Among students of all races, there was a modest shift toward classroom learning in March, but gains were largest among whites. Just more than half of white students were learning entirely in-person, compared to about a third of black and Hispanic students. Only 15% of Asian Americans were learning entirely in the classroom.

Progress has been equally uneven based on geography, the survey found.

Half of all students in the South and Midwest were learning entirely in-person in March, compared to less than 20% in the West and Northeast. Still, the Northeast saw the largest gains, with Connecticut doubling its share of fourth grade students learning fully in-person, from 17% to 35%.

Wyoming had the largest share of fourth-grade students attending full-time in the classroom, at 94%, while California had the lowest, with 5%. Schools in rural areas were the most likely to be opened, while schools in cities have been the slowest to reopen.

Across the country, younger children - they are less likely than adults to get seriously ill from COVID-19 - have returned to the classroom at higher rates.