The present article sets out to validate small-scale research projects as a tool to foster the integration of theory and practice as well as the development of a refl ective mindset in trainees in teacher training courses. This case study of the process followed by an experienced teacher carrying out research as part of a Master's degree in Teaching English traces the student's learning during her research process through an analysis of her interactions, both oral and written, with the thesis supervisor, as well as of the materials created for the pedagogical intervention planned and the data collection carried out as part of the action research process. This reconstruction of the trainee's developing understanding while working on her MA thesis reveals that learning does take place and is brought about by a mixture of different factors, such as the relation established between the theoretical concepts studied in the program and the actual teaching practice, the detachment brought about by the need to collect data and the interaction with the supervisor. Carrying out a research project also helps the trainee to refl ect on her own practice, and thus establish a refl ective mindset.Keywords: teacher training; EFL; CLIL; refl ection.Resumen: El presente artículo se propone validar los pequeños trabajos de investigación como una herramienta para profesores en formación que promueve la integración de la teoría con la práctica docente así como un acercamiento refl exivo a esta práctica. En él se presenta un estudio de caso del proceso seguido por una docente experimentada en la elaboración de una investigación como parte de sus estudios de Máster en el ámbito de la Enseñanza del Inglés como Lengua Extranjera. Para ello se analiza tanto su interacción oral y escrita con la directora de trabajo, como los materiales elaborados para la intervención pedagógica y la posterior recogida de datos. El análisis del proceso llevado a cabo por la estudiante nos permite concluir que la experiencia de investigación contribuye al aprendizaje del profesor en formación y le ayuda a refl exionar sobre su propia práctica docente.Palabras clave: Formación de profesorado; enseñanza del inglés como lengua extranjera; enseñanza bilingüe; refl exión. O ne of the challenges of any teacher training or teacher development program is to act as a catalyst of change, and thus to make sure trainees are able to incorporate what they learn in these programs into their teaching practice. As one way of meeting this challenge, and making the integration of theory into practice possible, many teacher training programs include small-scale (action) research projects as part of their training. In these small projects, teachers are encouraged to take one or several aspects of the techniques or approaches dealt with in the teacher training program, and try them out in a classroom situation, with the fi nal aim of improving their own teaching practice (Luneberg, Ponte, & Van de Vev, 2007). Apart from providing an opportunity for linking theory with p...