چکیده:
The present study investigated high school English language teachers’ perspectives on the usefulness of In-service Education and Training (INSET) classes on their Knowledge Base (KB). Three rounds of the Delphi study were designed: one qualitative study using semi-structured interviews and two quantitative ones. Twenty-nine teachers were selected based on purposive sampling. The criterion for sample selection was teachers’ participation in the INSET classes held by the Education and Training Organization of Guilan Province. The teachers were familiar with the Prospects and Vision textbook series and agreed to participate in the study. After conducting semi-structured interviews, common issues related to the teachers’ KB were extracted using MAXQDA version 12. Then, based on EFL teachers’ responses to the interview questions in the first Round (R1), the second Round (R2) was conducted, resulting in the development of a 27-item questionnaire on a five-point Likert-type scale addressing teachers’ KB to which the participants responded. The third Round (R3) was performed with the same questionnaire and participants to verify their views stated in R2. Paired samples t-tests were used to analyze the data in R2 and R3. The results showed conformity among teachers’ responses to the interviews and R2 and R3 questions. Teachers expected the classes to be more practical, focusing on step-by-step instruction and planning to enhance their pedagogical, technological, and content knowledge bases. The findings suggest that appropriate INSET programs need to be developed and implemented to promote teachers’ quality of practice and, thus, students’ learning.