Three years ago, the Pickerington school district in Ohio received what seemed like a wonderful windfall: a $1.6 million grant to launch a mobile “fab lab,” a kind of maker space with high-tech equipment for students to use.

Some of the equipment was precisely what students would use if they graduated and wanted to find work in manufacturing, or pursued a career in engineering.

But problems arose as teachers were trained to use some of the more complex machinery.