If you want to use Social Constr. in real life, there are moments where it is very efficiënt to give studenst a short instruction before they start their rich/multibehavior s.c. activities.
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A real live teacher or a well written PI in lesson (or in SCORM: RELOAD or eXe) can fullfill this role.
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.. So no against (to many) stand-alone PI, Yes to nice integrated PI.
(I still hope that lesson becomes an activity students can start, so they can construct complex matrix/choice exercises for languages and social sciences exercises. A kind of "promote this to student edit level" checkbox when the teacher creates an activity. When a student sees that activity he can select from a drop-down box student names: play the exercise of a fellow student or create/edit his own lessson constructb when he chooses his own name... )