Teacher's world gives feedback on the action. Student modifies actions in the light of feedback. Student reflects on action to modify description. Student adapts action in light of concept. Teacher adapts task goal in light of student's description.
Teacher reflects on action to modify description.
For maximum utility we would like to identify an element that caused learning directly AND could be manipulated by designers directly. What affects learners is learner actions, even if these are hidden mental actions. Not external actions by teachers, computers, or learners. The actions that most directly affect learning are probably things like interpretation and understanding cf. Not directly observable, although perhaps can get at them by interviews.