The Assumptions Teachers Make

First, educators make assumptions about the students who enter their classrooms. Sometimes these assumptions are accurate, sometime not. Sometime these assumptions inhibit teaching and learning, sometimes they promote it. These assumptions can be cultural or socioeconomic, reflect expectations regarding prior knowledge and experience, reflect certain values or expectations. Perhaps the most difficult aspect of these assumptions to overcome is that neither the teacher nor the student may be aware of them.  

Second, educators create lessons based on their assumptions about how teaching and learning occurs; even those assumptions are not conscious, these assumptions can be seen in every strategy used in a classroom. 

Third, educators direct their students to perform tasks, and the degree to which the students can complete these with accuracy and to the specifications as judged by the educator is accepted as a proxy for the degree to which the student learned. 

In my experience, educators (including those who have been in the field for decades) hold too simplistic assumptions about their students. Cognitive and learning scientists are discovering many previously unrecognized (or dismissed) aspects of students