Research on teaching and teacher research has a long history. However, in the field of the education of deaf and hard of hearing students, this research is limited. The study addresses one particular area of research on teaching and teacher research: practical knowledge of teachers of deaf and hard of hearing students. Practical knowledge is defined as how educators think about their classroom practice. By means of a survey designed and tested by the researcher, four hierarchical groups (beginning education students, graduating education students, novice teachers, and experienced teachers) in the education of deaf and hard of hearing students were surveyed on their practical knowledge. Practical knowledge codified as images, rules of practice, and practical principles. Results were measured to demonstrate for categories and characteristics of practical knowledge storage among prospective and current teachers of deaf and hard of hearing students. The instrument was designed as an assessment tool to measure aspects of this knowledge, apply it to levels of pedagogical expertise, and expand research in this area.