School districts that serve tens of thousands of Colorado students are using discredited or inconsistent approaches to teach children how to read, contributing to the state’s persistently low rates of reading proficiency.

A Chalkbeat investigation found the state’s 30 largest school districts and three charter networks together use three dozen core curriculums, often different ones in neighboring schools. Experts on curriculum say such variation can be found in many states but should raise questions about which students get left behind by the mish-mash of methods.

Six in 10 third-graders can’t read proficiently, even eight years after a landmark reading law that earmarked millions annually to help struggling readers. One reason for this is that many schools rely on methods that aren’t supported by research.

Often, the students who lose out are those who already face other challenges, like poverty and disability.

“It’s astonishing how much the United States under-teaches all of its students, but it particularly lowers the bar for its disadvantaged students,” said David Steiner, executive director of the Johns Hopkins Institute for Education Policy in Baltimore. “It’s crucial at pre-kindergarten, kindergarten, grades one and two that rigorous materials are used.”

Now, amid activism by parents of dyslexic children, action from frustrated lawmakers, and news coverage about flawed instructional approaches, state leaders are taking new steps to boost reading skills. Curriculum — the roadmap for what and how teachers teach — is one front in that effort, with a new law giving state education officials stronger levers to ensure that schools are using scientifically sound methods for reading instruction.