ITiCSE'20 WG 2

Capturing and Characterising Notional Machines

Mon, Jun 15, 2020Fri, Jun 19, 2020

Matthias Hauswirth collaborating on Capturing and Characterising Notional Machines as part of the ITiCSE 2020 Working Group 2 (online), lead by Sally Fincher, Johan Jeuring, and Craig S. Miller.


A notional machine is a pedagogic device to assist the understanding of some aspect of programs or programming. It is typically used to support explaining a programming construct, or the user-understandable semantics of a program. For example, a variable is like a box with a label, and assignment copies or moves a value into that box. This working group will capture examples of notional machines from actual pedagogical practice, as expressed in textbooks (or other teaching materials) or used in the classroom. We will interview at least 30 teachers about their experience with, and perceptions of, the use of notional machines in teaching. Using the interviews, we will work on devising and refining a form to characterise essential features of notional machines. We will also attempt to relate them to each other to describe potential learning sequences or progressions. The working group report will contain descriptions of notional machines used at different levels in education, in different countries, by many teachers. The resulting catalogue of notional machines will allow a teacher to select a machine for a particular use, permit comparison between them, and provide a starting point for further categorization and analysis of notional machines. Additionally, we will make more theoretical explorations. We will explore a variety of presentational formats, examining what is necessary and what superfluous; we will look for dimensions of comparison and will examine how notional machines are instantiated across the discipline. We argue that the creation and use of notional machines is potentially a signature pedagogy for computing [1] and that creating and using notional machines represents a certain level of pedagogic sophistication that might be an indicator of pedagogic content knowledge (PCK).