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This report defines notional machines (NMs), and provides a series of definitional characteristics by which they may be identified. Over several sections, it includes a first-hand report of the origin of NMs, reports a systematic literature review to track the use and development of the concept, and presents a small collection of examples collected through interviews with experienced teachers. Additionally, the report presents NMs in a common format, and makes some preliminary explorations of their use in practice, including examples of instructors using multiple NMs in sequence. Approach and method are fully detailed in evidential appendices, to support replication of results and adoption/adaptation of practice.

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. Capturing and Characterising Notional Machines Sally Fincher, Johan Jeuring, Craig S Miller Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for third-party components of this work must be honored. For all other uses, contact the owner/author(s). ITiCSE 2020,,Trondheim, Norway © 2020 Copyright held by the owner/author(s). 978-1-4503-0000-0/18/06...$15.00 https://doi.org/10.1145/1234567890 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).

This paper uses an approach that differs from conventional interview research to trace the individual trajectories of two computing graduates. In this approach, interviews are considered a dialogic process and analysis is a case-centred process that explores similarities and differences in participants' trajectories. This approach allows us to probe the experience and lasting value of computing education beyond graduation. In this extended analytic approach we expose participants' sense of professionalism and we connect this with the concept of accountable disciplinary knowledge (ADK). ADK has previously only been applied to students' experiences and identity formation at university. The approach taken in this work allows us to see the extension of ADK into the workplace.