HCD.6.1:4.4 - Change incidental features and then combine contributions

Keep the target relation while changing a feature that could have become an unintended cue. Alternatively, change the target while preserving that cue. The learner’s response now helps locate what was learned from the first task.

Once the relevant distinctions are accessible, combine those needed together in the encompassing work. HCD.6 prepares sufficiently whole tasks; HCD.10 selects variation and support changes from their purpose. One-at-a-time contrast is a teaching option, not a claim that real work contains only one changing feature.

Choose the next comparison from an actual confusion when one is available. Additional comparisons are useful when they reveal or correct a difference that matters. They need not fill every practice episode.