Teachers need to understand that their authority does not make them infallible. Critical thinking requires the ability to question one's own assumptions and prejudices as well as those of others. Students depend on teachers to be able to recognize the kinds of bias the teacher brings into the classroom if that bias might cause a teacher to prejudge or misjudge a student's motives and intentions. This means taking an extra step or two to confirm any conclusions about students, relying on evidence instead of impression.
High school teachers need to be able to establish context. This is particularly important in situations where the teacher is thrown into the role of conflict resolution between students, themselves and other teachers, or teachers and administrators. Rules and facts are inadequate to form a sound judgement in the absence of context. The situations of each person, the history of the conflict and the catalyst are required to put a situation into its full critical perspective.
Whether the teacher is researching a topic for class, preparing for a parent-teacher conference or attending a meeting of her union, she will need to seek as much relevant information as possible on the topics or issues under review. Critical thinking begins with the awareness that you may not have all the answers, and that gathering information is essential to more fully comprehend the topic or issue.
Every teacher has goals, whether they are teaching goals or professional goals. Critical evaluation of goals involves learning what conditions might be immediately necessary for the achievement of those goals, then analyzing what intermediate steps might have to be taken to facilitate development of those conditions. Sometimes this kind of analysis of goals will reveal that goals are either inadequate or unachievable. Then the teacher can reassess those goals, reformulate them, and critically evaluate them again.