Teaching, one of the most compelling professions that leaves its mark on children and young people in raising individuals who determine the future of society, is subject to an inevitable transformation in the dizzying winds of change of the 21st century. Developing technology and changing children and young people make it mandatory for teachers to practice a multifaceted teaching profession. Instead of taking ready-made and presenting existing information to students like packaged food, the teacher of the 21st century should fulfill teaching as a profession responsible for examining the benefit, validity, and reliability of the information produced. In addition to exploring the validity, reliability, and benefit of information, they should produce valid, reliable, and valuable information using existing information and are expected to contribute to their students doing this. It has become crucial for teachers to have the identity of a “researcher teacher” that will contribute to developing their questioning skills. This book, titled “Development of the Researcher Teacher,” not only contributes to the training of future teachers but also serves as a guide for teachers and teacher candidates in terms of finding valid and reliable solutions to the problems that current teachers may experience. The modern world accepts the role of research in the development of countries. A country's ability to compete with other countries on a global scale and to be strong is closely related to the share it allocates from its budget for research and the number of trained people working as researchers. Therefore, training more researchers requires teachers to have the knowledge and skills to conduct research.