Big Ideas of Cryptography in Primary School

We present a learning path on cryptography for primary school students (Grade 5), which we designed and tested. The project aims to raise initial awareness of the core ideas of modern cryptography, which are fundamental concepts for becoming informed and active citizens in modern digital society. For this reason, we designed a progression of unplugged activities (sometimes integrated with task-specific, block-based programming environments) to expose students to different cryptographic techniques, where each new activity is motivated by an analysis of the criticalities encountered previously. We used unplugged activities to show that Computer Science (CS) does not necessarily imply the use of digital devices and to allow students to focus on its general scientific principles. We describe the designed learning module, discuss the main hinges in the experiment, and reflect on the lessons learned. The final evaluation showed excellent learning outcomes and high satisfaction with the activities. As cryptography uses mathematical tools (e.g., modular arithmetic, statistics), some parts of which are within reach of primary school children but rarely taught to them, it was possible to dwell on these aspects, making them experience mathematical objects in a non-standard context, and also stimulating a greater awareness of the impact of mathematics and CS in everyday life.