As late as 1913, half of the country's schoolchildren were enrolled in the country's 200,000 one-room schools. But after the First World War, one-room schools started to close, as people moved into cities and small schools started to consolidate.
So for most of us, the one-room school is now just folklore -- the kind that Laura Ingalls Wilder brought to life in "Little House on the Prairie."
It's been a long time since the farmlands near Lansing, Mich., were prairie.
Brenda Hydon (left) teaches a class of 18, ages five to 12, at the Strange one-room school. Founded in 1879, the kids still sit in the exact same classroom, except now they learn on iPads. But one teacher job requirement hasn't changed across all those years: being self-sufficient.
"In a big school the teacher would call in the guidance counselor -- that would be you," said Petersen. "Or complain to the principal -- that would be you."
"Yes!" said Hydon. "At first, it was overwhelming. But now it's part of the job. You just have to [have] the instinct to know what to do and what to say."
And here the lessons are not just about math or science, but about older children helping the younger ones with things like learning how to read.
And there is an unusual teaching tool that may only work in a one-room school: eavesdropping. It sure helps first grader Thomas Trygier: "'Cause when I was in kindergarten, I was, like, listening to all the third grade stuff," he told Petersen. "So I learned a lot in kindergarten."
"I remember last year he came from kindergarten, 'Mom, what is the Silver War?'" said his mother, Cynthia. "He didn't know it was Civil War. But he hears the older kids talking."
Which is why Cynthia Trygier (herself a teacher at a Christian high school) wanted seven-year-old Thomas in a one-room school, even though there were bigger schools closer to their home.
"Kindergarten, he was already moved up into first grade reading and math, and it was a smooth transition," she said. "I don't want him to grow up too fast; I want him to enjoy his childhood. And in this school, he is still a first grader, but he's doing second and third grade work in reading and math."
And at Strange, there are other lessons of life; students must clean the school every day.
Petersen asked, "What are you trying to teach there?"
"Responsibility," said Hydon. "I think responsibility goes with every aspect of life that we do. I mean, it carries over to a work ethic that everyone should have instilled in them.'"
You might think kids would miss things like team sports, but they don't. At Divide the local one-room schools get together to make up a track or basketball team.