When Nathanael was in kindergarten, he told his mother, Diana Lopez, that he did not want to return to school — ever. His teacher yelled at him, he said. And when Ms. Lopez picked him up from school, he would often immediately start to cry.

Nathanael has autism, and in a busy classroom of 25 children, the teacher seemed to have few strategies for working with him, Ms. Lopez recalled.

This year at a new school, Nathanael, 7, was happier. He shared a teacher with only six other students — not in one classroom, but in the entire school.

Nathanael attended a microschool, an increasingly popular type of super-small, largely unregulated private school, often serving fewer students than are enrolled in a single classroom at a traditional school.

The programs are benefiting from two trends: Since the Covid-19 pandemic disrupted schooling, many parents have rethought their children’s education, and are open to nontraditional options. And Republican state lawmakers and donors, who have long supported private-school choice, have increasingly directed money toward microschools across the country, saying they give parents a chance to withdraw from school districts at a reasonable price — typically $5,000 to $10,000 per year.

Microschool students are usually registered with their states as home-schoolers. But the new generation of microschools, like the program Nathanael attended, Kingdom Seed Christian Academy, operate more like modern-day one-room schoolhouses, meeting in homes, church basements and storefronts.