CHILLICOTHE, Ohio — When Toby Bouska Jr. started assembling cabs for Kenworth semitrucks last year, he learned the ropes by observing longtime workers at the factory. But it wasn’t exactly engaging, and he didn’t get much practice doing the job himself.

“It’s them doing the job, and you just have to watch,” said Mr. Bouska, 21, who works at Kenworth’s plant in Chillicothe. “I’m not really good at just sitting there watching.”

But then his managers had him train in a new way: with a high-tech headset. They gave him a Microsoft HoloLens, a device that blends digital imagery with the real world. When he wore the headset, it overlaid digital arrows and diagrams over the parts he was looking at, helping to guide his work.

“With the HoloLens, it’s just you and the directions,” Mr. Bouska said. He said he had picked up his first new task in about 20 minutes.