Unless learning goals are clear, it is impossible to hold students and teachers accountable. Also, in-depth exploration of ideas takes longer than the more familiar broad and superficial survey of concepts. Teachers often feel a need to direct lessons to insure that students get the right information. Teachers frequently give students too much independence without adequately modeling thinking, structuring the situation, or providing feedback. Teachers who have not used technology as a cognitive tool have difficulty incorporating technology into the classroom.
Teachers have difficulty designing assessments that tap student understanding.
The artifacts they ask students to produce do not always require students to synthesize information or generate new conceptual representations. Moreover, evaluating the artifacts is difficult. Enacting project-based science.