An apprentice could reproduce the shape of a wooden joint after watching her teacher several times. When given a board of a different thickness, however, she made the familiar cuts and produced a joint that would not fit. The teacher asked her to explain what each cut was meant to achieve. She discovered that she had remembered distances from the edge without understanding how those distances depended on the thickness of the material. They then built two joints with different measurements but the same relation between their parts. The apprentice was not asked to forget the original example. She was asked to distinguish its adjustable features from its structural requirements. Remembering an example can support later work, but successful adaptation depends on knowing which relationships must survive when the visible details change. Exact reproduction is therefore evidence of one accomplishment, not evidence of every accomplishment the original task may require.