The teacher's clarity ensures that struggling learners focus on essential understandings and skills; they don't drown in in a pool of disjointed facts. Similarly, the teacher ensures that advanced learners spend their time grappling with important complexities rather than repeating work on what they already know.
Looking at the extremes might be a good way to evaluate how your students are doing. Think about those struggling learners. Does it appear that they are focused on essential understanding and skills or drowning in a pool of disjoinged facts? How about your advanced students? Are they grappling with important complexities or repeating work on what they already know? Food for thought!