2022 Volume 46 Issue 1 Pages 79-90
Many teachers of English in secondary schools in Japan find it challenging to achieve an optimal instructional speech (IS) in English. Meanwhile, research pointed out that both IS and teacher development relate to teacher self-efficacy (TSE). Here we conducted a case study of three teachers with different years of teaching experience. Quantitative analysis of the IS data and qualitative analysis of the interview data, collected via "practical argument," operated to see how IS behavior and the principles (premises) relate to TSE. The results revealed a connection of TSE with the IS, representing a certain level of fluctuation in respective teachers: the novice teacher overused Japanese speech due to the relationship building and student's understanding of English; the less experienced teacher did so with an emphasis on the entrance examination but few relationship building; and the experienced teacher marked less fluctuated TSE via English IS, caused by the pleasure through students' collaboration and the expectation of their growth.