Labelling drill

Two kinds of diagram. Drawn diagrams give you numbered arrows and a tray of names — with more names than arrows, distractors from the same region, and names reusable, so elimination gets you nowhere. Plate drills take a real Gray's plate and cut every printed label out of it: you drag each label back to the box it came from, with its leader line still pointing at the structure. Either way, nothing is marked right or wrong until you submit.