Search

International audience; Introductory programming courses (CS1) are difficult for novices. Inspired by Problem solving followed by instruction and Productive Failure approaches, we define an original "necessity driven" learning design. Students are put in an apparently well-known situation, but this time they miss an essential ingredient (the target concept) to solve the problem. Then, struggling to solve it, they experience the necessity of that concept. A direct instruction phase follows. Finally, students return to the problem with the necessary knowledge to solve it. In a typical CS1 learning path, we recognise a challenging "rollercoaster of abstraction". We provide examples of learning sequences designed with our approach to support students when the abstraction changes (both upward and downward) inside the programming language, for example, when a new construct (and the related syntactical, conceptual, and strategic knowledge) is introduced. Also, we discuss the benefits of our design in light of Informatics education literature.

International audience; La cryptographie est un domaine propice pour étudier les interactions entre mathématiques et informatique. Nous présentons la conception d'une situation didactique basée sur un système cryptographique asymétrique. Cette situation a été expérimentée dans une formation d'enseignants.

International audience; We report our experience of an extracurricular online intervention on cryptography in Grade 10. Our first goal is to describe how we taught some fundamental cryptography ideas by making students encounter a progression of representative cryptosystems, from classical to modern, and discover their characteristics and limitations. We used Snap! (a visual programming language) to realize hands-on activities: block-programming playgrounds (a form of task-specific programming languages) to experiment with cryptosystems, and an interactive app to support an unplugged (albeit remote) Diffie-Hellman key agreement. After experimenting with each system, the students were involved in a Socratic discussion on how to overcome the discovered limitations, motivating the introduction of the following system in our path. Our second goal is to evaluate the students' perceptions and learning of cryptography core ideas. They appreciated the course and felt that, despite being remote, it was fun and engaging. According to the students, the course helped them understand the role of cryptography, CS, and Math in society and sparked their interest in cryptography and CS. The final assessment showed that the students well understood the cryptography ideas addressed. Our third goal is to discuss what worked and areas of improvement. The "remote-unplugged" Diffie-Hellman, where the meeting chat was a metaphor for the public channel, engaged the students in understanding this groundbreaking protocol. Overall, they praised the activities as engaging, even when challenging. However, a strong "instructor blindness" induced by remote teaching often prevented us from giving the students the right amount of guidance during the exploration activities.