MIDLOTHIAN, Va. — “Let’s make sure we’re clear on terms,” the instructor said, summoning the next presentation slide onto the big screen behind him. Obscurities such as “borrow excavation,” “grubbing” and “subbase” didn’t faze the 21 apprentices in the room. They were almost all young men, many sporting baseball caps and sunburned necks. They’d been working on construction sites for months.
