Impact of Beam Line for School on teaching activities at our school and the EXTRA experiment at DESY 2021.

Beamline for Schools (BL4S) is an annual international competition in high-energy particle physics for high school students, organized by CERN. The students are asked to propose an experiment that can be realized at a particle beam line. Experienced scientists evaluate the proposals and select two winning teams that are then invited to perform their experiments with the help of professional scientists. The winners of the 2021 edition, the team EXTRA from Italy and the team Teomitztli from Mexico were invited to perform their measurement at the DESY (Hamburg) test beam facilities. The EXTRA (Electron X-ray Transition RAdiation) experiment was aimed to study the energy spectra and the angular distribution of the transition radiation (TR) emitted by fast electrons crossing a regular radiator. From teacher's perspective the experience of mentoring a team has been extremely beneficial to our professional development. We will describe the effects that the participation in BL4S had on us, on our students and how it has impacted our approach to teaching STEM subjects.