Abstract

This paper presents an in-action teacher training program for 5th and 6th grade (10-12 years-old) mathematics teachers in the Andorran school, adapted from the Lesson Study to be implemented on a large scale. The program, called Andorran Lesson Study (ALS), overcame limitations by recording and mass viewing classroom videos, combined with pre-and post discussion sessions. The combination of teacher observations and feedback showed a significant contribution of ALS to professional development in math teaching, with notable progress in the utilization of learning opportunities, a wider range of mathematical representations, and effective communication about and around mathematics. ALS also contributed to improving the effectiveness of developing math competencies promoted by the Andorran curriculum. In conclusion, ALS is presented as a viable alternative for continuous teacher training, allowing for logistical and cultural adaptation to different school contexts and organizations.