Online Unplugged and Block-Based Cryptography in Grade 10

TL;DR

This paper describes an online, unplugged, and block-based cryptography teaching intervention for 10th graders, emphasizing core ideas through visual programming and interactive activities, with positive student engagement and understanding.

Contribution

It introduces a novel remote cryptography curriculum using Snap! to teach core concepts through hands-on and unplugged activities, with evaluation of student perceptions and learning outcomes.

Findings

Students found the course engaging and interesting.

Core cryptography ideas were well understood by students.

Remote Diffie-Hellman activity was effective and engaging.

Abstract

We report our experience of an extracurricular online intervention on cryptography principles in 10th grade. This paper's first goal is to present the learning path we designed, influenced by cryptography core ideas rather than technical knowledge. We will detail how we used Snap! (a visual programming language) to realize hands-on activities: programming playgrounds to experiment with cryptosystems and their limits, and interactive support for an unplugged activity on the Diffie-Hellman key exchange. The second goal is to evaluate our intervention in terms of both student perceptions and learning of core cryptography ideas. The students appreciated the course and felt that, despite being remote, it was fun, interesting, and engaging. They said the course helped them understand the role of cryptography, CS, and Math in society and sparked their interest, especially in cryptography and CS. The third goal is to discuss what worked well and areas of improvement. Pedagogically, remote teaching caused high "instructor blindness" and prevented us from giving the optimal amount of guidance during the exploration activities with Snap! playgrounds, making them sometimes too challenging for total programming novices. On the other hand, the "remote-unplugged" Diffie-Hellman worked well: it embodies a coherent metaphor that engaged the students and made them grasp this groundbreaking protocol. The students praised the activities as engaging, even when challenging. The final assessment showed that the core cryptography ideas were well understood.