An attitude is a framework that affects how a person thinks and acts about the world. Because people's belief systems impact how they behave, internal values may reveal themselves in a person's actions. If a teacher has a negative attitude towards education, his job or his students, it may influence his performance as an educator.
A teacher's own beliefs -- whether conscious or subconscious -- can profoundly affect his students. According to Education World, a teacher can heavily influence a student's interest in science. Girls, who are notoriously underrepresented in professional science careers, are especially motivated towards or away from science by their teachers, more so than by their parents or peers. According to Dr. Michael Papadimitriou, "Girls described situations in which the personality traits of their teachers were more powerful and influential than course content or instructional strategies with respect to their opinions of their experiences."
A large part of teaching is modelling and support. If a teacher appears to not like or care about a particular subject -- or student -- then he will be unable to foster a supportive learning environment. A teacher's personal value systems may be more evident to the student than the teacher realizes. The achievement gap, defined by the U.S. Department of Education as "the difference in academic performance between different ethnic groups," is a nationally recognized problem. Kids at-risk for performing below the achievement gap may realize that a teacher views them as such, and will not be able to achieve their full potential. In addition, a teacher with a negative attitude may not be as approachable as teachers with positive attitudes. A student may be less likely to seek clarification about a particular subject if he does not want to ask his teacher for more help.
Attitude could also affect how well a teacher prepares for lessons. According to a study done by Ankara University in Turkey and reported on Science Direct, teachers who have positive attitudes towards teaching rubrics (which help teachers to assess learning based on specific criteria) worked harder on the rubrics. Teachers with positive attitudes towards rubrics did not simply use rubrics to assign grades to students, as the teachers with negative attitudes towards rubrics did. According to the study, teachers with positive attitudes towards rubrics looked at "the development of students' higher order thinking skills" and "to what extent the students used their knowledge and skills in real life situations." How a teacher feels about prepared lessons and student assessment could affect how deeply he examines student work, and he may have a more holistic position on academic evaluation.