Since year 1999, the Legnaro National Laboratories (LNL), one of the four laboratories of the Italian Institute for Nuclear Physics (INFN), has been promoting scientific culture at a local and national level by sharing the outcomes of its research, with a specific focus on their impact on modern society.

Outreach programs are intended for both general public and students, especially those in higher education, i.e. the 14 - 19 age group. In this context, LNL has been offering a two-week summer internship to students in their fourth year of high school. The internship aims to introduce students to the world of scientific and technological research through meetings with researchers working in the field of fundamental and applied physics and involving them in experimental activities. A further objective is to provide university guidance in the STEM disciplines.

The students are organized in small working groups of 2 - 4 people led by a tutor, in charge of planning and leading the daily activities. This allows them to collaborate in teamworks, stimulating their interpersonal and coordination skills. The subjects proposed for the group activities cover fundamental and applied nuclear physics, accelerator physics, natural radioactivity, detector development, mechanical and electronics engineering and safety. The work and achievements of all groups are presented during a final public event, to which, families and teachers are also invited.

The LNL internship format remains valid and successful with students, teachers, and schools, even after 25 years. It has enabled the laboratory to establish fruitful relationships with numerous schools across the national territory, also allowing them to work together on more outreach projects, managed both locally by LNL and nationally by the INFN.

The national project STAGE, started in 2025, extends the LNL experience to other INFN Divisions. The project is financed by the Coordination Committee for the Third Mission (CC3M), which supports outreach initiatives at a national level. The STAGE project is coordinated by LNL and currently includes the participation of the Pavia and Ferrara Divisions, with the aim of expanding the participation to further Divisions in the coming years.

Keywords: Education, sharing scientific knowledge, scientific internship, experimental activities.