MINNEAPOLIS (AP) — A group of high school math teachers have saved the Anoka-Hennepin school district about $175,000 by creating their own online textbook.

District technology manager Bruce Dewitt says the district was due to replace its 10-year-old textbooks on statistics and probability this year when three math teachers stepped forward with a better idea.

They proposed developing a math curriculum that would fit Minnesota’s standards better than mass-produced textbooks. It’s based on free software from a California nonprofit organization.

The teachers spent 100 hours each this summer developing the lessons and another nine teachers edited their work. The district wound up spending about $15,000 for material that could have cost $200,000.

The district’s high schools are teaching out of the new curriculum this year.

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