Informatics in Education

Concurrency is often perceived as difficult by students. One reason for this may be due to the fact that abstractions used in concurrent programs leave more situations undefined compared to sequential programs (e.g., in what order statements are executed), which makes it harder to create a proper mental model of the execution environment. Students who aim to explore the abstractions through testing are further hindered by the non-determinism of concurrent programs since even incorrect programs may seem to work properly most of the time. In this paper we aim to explore how students’ understanding these abstractions by examining 137 solutions to two concurrency questions given on the final exam in two years of an introductory concurrency course. To highlight problematic areas of these abstractions, we present alternative abstractions under which each incorrect solution would be correct.

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.

When we “think like a computer scientist,” we are able to systematically solve problems in different fields, create software applications that support various needs, and design artefacts that model complex systems. Abstraction is a soft skill embedded in all those endeavours, being a main cornerstone of computational thinking. Our overview of abstraction is intended to be not so much systematic as thought provoking, inviting the reader to (re)think abstraction from different – and perhaps unusual – perspectives. After presenting a range of its characterisations, we will explore abstraction from a cognitive point of view. Then we will discuss the role of abstraction in a range of computer science areas, including whether and how abstraction is taught. Although it is impossible to capture the essence of abstraction in one sentence, one section or a single paper, we hope our insights into abstraction may help computer science educators to better understand, model and even dare to teach abstraction skills.

Controlling complexity through the use of abstractions is a critical part of problem solving in programming. Thus, becoming proficient with procedural and data abstraction through the use of user-defined functions is important. Properly using functions for abstraction involves a number of other core concepts, such as parameter passing, scope and references, which are known to be difficult. Therefore, this paper aims to study students’ proficiency with these core concepts, and students’ ability to apply procedural and data abstraction to solve problems. We collected data from two years of an introductory Python course, both from a questionnaire and from two lab assignments. The data shows that students had difficulties with the core concepts, and a number of issues solving problems with abstraction. We also investigate the impact of using a visualization tool when teaching the core concepts.

The notion of algorithm may be perceived in different levels of abstraction. In the lower levels it is an operational set of instructions. In higher levels it may be viewed as an object with properties, solving a problem with characteristics. Novices mostly relate to the lower levels. Yet, higher levels are very relevant for them as well. We unfold the importance of higher level abstractions for novices, by demonstrating the role of declarative observations of algorithmic problems, and the benefit of developing awareness of such observations in algorithmic problem solving. This is shown in a two-stage study, which first reveals the unfortunate lack of declarative observations, and then displays comparative results of experimental and control groups, which stems from different awareness and competence with declarative observations.

Computer science students often evaluate the behavior of the code they write by running it on specific inputs and studying the outputs, and then apply their comprehension to a more general understanding of the code. While this is a good starting point in the student’s career, successful graduates must be able to reason analytically about the code they create or encounter. They must be able to reason about the behavior of the code on arbitrary inputs, without running the code. Abstraction is central for such reasoning.

Teaching software engineering (SWE) as a core computer science course (ACM, 2013) is a challenging task. The challenge lies in the emphasis on what a large-scale software means, implementing teamwork, and teaching abstraction in software design while simultaneously engaging students into reasonable coding tasks. The abstraction of the system design is perhaps the most critical and theoretical part of the course and requires early engagement of the students with the necessary topics followed by implementation of the abstract model consistently. Normally, students would take such courses in the undergraduate curriculum sequence after data structures and/or object-oriented design/programming. Therefore, they would be able to learn about systematic modeling of software as a system. In this work, we address how to facilitate the teaching of SWE by introducing abstract modeling. Furthermore, functional decomposition is reviewed as a critical component which in turn, requires understanding of how different tasks are accomplished by enterprise software. Combining such pieces with concepts of architecture and design patterns of software provides foundational knowledge for students to be able to navigate around enterprise software in the real world.

Despite a growing effort to implement computational thinking (CT) skills in primary schools, little research is reported about what CT skills to teach at what age. Therefore, the research questions that guide this study read: (1) How is age related to students' success in computational thinking tasks? (2) How are computational thinking tasks perceived by students? (3) How do students' experience learning with respect to computational thinking? 200 primary school students between the age of 6 and 12 participated in this study. These students got introduced to two CT subjects: abstraction and decomposition. We found that age seems to be related with these concepts, with an interaction effect for gender in the abstraction task. No differences found between young and older students in the constructs perceived difficulty, cognitive load, and flow indicate that young primary school students can engage in learning these CT skills.

For over a decade, a declarative approach to problem solving based on the use of abstract data types (ADTs) has been taught to high-school students as part of the logic programming instructional unit. We conducted a study aimed at assessing students' problem-solving processes when utilizing ADTs. The findings indicated that students' strategies that diverged from the conceptual model often cause the students to develop incorrect programs. Specifically, students have difficulties in establishing correct mapping between the problem and its abstract model - the corresponding ADT, and in establishing proper connectivity between layers of abstraction related to different stages of the problem-solving processes (e.g., between distinct programming modules). These difficulties are apparently associated with general difficulties that novices encounter when learning programming, and with the cognitive load encountered when dealing with high levels of abstraction. With the intention to reduce student difficulties, we suggest using an instructional approach designed to gradually educate the students toward attaining proficiency as ``problem solvers'' through the use of integrative knowledge and autonomous problem-solving techniques. This approach should be further evaluated regarding its feasibility and applicability to reducing students' difficulties in dealing with abstraction processes.

Abstract thinking is a vital skill when learning computer science. Object technology and the concepts it is based upon make this skill even more crucial. However, previous research works show that students in top universities as well as experienced practitioners in industry encounter difficulties in thinking in abstract terms while practicing object oriented development. In this paper we suggest an iterative teaching methodology for supporting students in learning object oriented concepts. The suggested methodology is based on familiarizing students with modeling languages and tools at the early stages of their learning and iterating between model and code. We theoretically examine the contribution of modeling languages, in particular UML, to abstract thinking and consequently to the understanding of object oriented concepts and present some observations acquired during a trial execution of this methodology in a university course.