HCD.10:4.5 - Interleave only when Selection Is Part of the Target

Mix task families when the learner must recognize which Method, relation, calculation, check, or response applies and when their similarity makes that discrimination meaningful. Require the learner to state why one route fits and why a serious neighbor does not. Preserve category similarity, order, support, and result so that a failure can be interpreted.

When the basic operation is new or still unstable, begin with blocked or stable supported episodes if that makes the action learnable and observable. Introduce mixing after the learner can perform the constituent action sufficiently for selection to become the real difficulty. Interleaving is a candidate, not a default schedule.