Neil C.C. Brown

Restart: The Resurgence of Computer Science in UK Schools

Computer science in UK schools is undergoing a remarkable transformation. While the changes are not consistent across each of the four devolved nations of the UK (England, Scotland, Wales and Northern Ireland), there are developments in each that are moving the subject to become mandatory for all pupils from age 5 onwards. In this article, we detail how computer science declined in the UK, and the developments that led to its revitalisation: a mixture of industry and interest group lobbying, with a particular focus on the value of the subject to all school pupils, not just those who would study it at degree level. This rapid growth in the subject is not without issues, however: there remain significant forthcoming challenges with its delivery, especially surrounding the issue of training sufficient numbers of teachers. We describe a national network of teaching excellence which is being set up to combat this problem, and look at the other challenges that lie ahead.

37 Million Compilations: Investigating Novice Programming Mistakes in Large-Scale Student Data

Previous investigations of student errors have typically focused on samples of hundreds of students at individual institutions. This work uses a years worth of compilation events from over 250,000 students all over the world, taken from the large Blackbox data set. We analyze the frequency, time-to-fix, and spread of errors among users, showing how these factors inter-relate, in addition to their development over the course of the year. These results can inform the design of courses, textbooks and also tools to target the most frequent (or hardest to fix) errors.

Bringing computer science back into schools: lessons from the UK

Computer science in UK schools is a subject in decline: the ratio of Computing to Maths A-Level students (i.e. ages 16--18) has fallen from 1:2 in 2003 to 1:20 in 2011 and in 2012. In 2011 and again in 2012, the ratio for female students was 1:100, with less than 300 female students taking Computing A-Level in the whole of the UK each year. Similar problems have been observed in the USA and other countries, despite the increased need for computer science skills caused by IT growth in industry and society. In the UK, the Computing At School (CAS) group was formed to try to improve the state of computer science in schools. Using a combination of grassroots teacher activities and policy lobbying at a national level, CAS has been able to rapidly gain traction in the fight for computer science in schools. We examine the reasons for this success, the challenges and dangers that lie ahead, and suggest how the experience of CAS in the UK can benefit other similar organisations, such as the CSTA in the USA.

Blackbox: a large scale repository of novice programmers' activity

Automatically observing and recording the programming behaviour of novices is an established computing education research technique. However, prior studies have been conducted at a single institution on a small or medium scale, without the possibility of data re-use. Now, the widespread availability of always-on Internet access allows for data collection at a much larger, global scale. In this paper we report on the Blackbox project, begun in June 2013. Blackbox is a perpetual data collection project that collects data from worldwide users of the BlueJ IDE -- a programming environment designed for novice programmers. Over one hundred thousand users have already opted-in to Blackbox. The collected data is anonymous and is available to other researchers for use in their own studies, thus benefitting the larger research community. In this paper, we describe the data available via Blackbox, show some examples of analyses that can be performed using the collected data, and discuss some of the analysis challenges that lie ahead.

Frame-Based Editing: Easing the Transition from Blocks to Text-Based Programming

Block-based programming systems, such as Scratch or Alice, are the most popular environments for introducing young children to programming. However, mastery of text-based programming continues to be the educational goal for students who continue to program into their teenage years and beyond. Transitioning across the significant gap between the two editing styles presents a difficult challenge in school-level teaching of programming. We propose a new style of program manipulation to bridge the gap: frame-based editing. Frame-based editing has the resistance to errors and approachability of block-based programming while retaining the flexibility and more conventional programming semantics of text-based programming languages. In this paper, we analyse the issues involved in the transition from blocks to text and argue that they can be overcome by using frame-based editing as an intermediate step. A design and implementation of a frame-based editor is provided.

Alloy: fast generic transformations for Haskell

Data-type generic programming can be used to traverse and manipulate specific parts of large heterogeneously-typed tree structures, without the need for tedious boilerplate. Generic programming is often approached from a theoretical perspective, where the emphasis lies on the power of the representation rather than on efficiency. We describe use cases for a generic system derived from our work on a nanopass compiler, where efficiency is a real concern, and detail a new generics approach (Alloy) that we have developed in Haskell to allow our compiler passes to traverse the abstract syntax tree quickly. We benchmark our approach against several other Haskell generics approaches and statistically analyse the results, finding that Alloy is fastest on heterogeneously-typed trees.

Novice Java Programming Mistakes: Large-Scale Data vs. Educator Beliefs

Teaching is the process of conveying knowledge and skills to learners. It involves preventing misunderstandings or correcting misconceptions that learners have acquired. Thus, effective teaching relies on solid knowledge of the discipline, but also a good grasp of where learners are likely to trip up or misunderstand. In programming, there is much opportunity for misunderstanding, and the penalties are harsh: failing to produce the correct syntax for a program, for example, can completely prevent any progress in learning how to program. Because programming is inherently computer-based, we have an opportunity to automatically observe programming behaviour -- more closely even than an educator in the room at the time. By observing students’ programming behaviour, and surveying educators, we can ask: do educators have an accurate understanding of the mistakes that students are likely to make? In this study, we combined two years of the Blackbox dataset (with more than 900 thousand users and almost 100 million compilation events) with a survey of 76 educators to investigate which mistakes students make while learning to program Java, and whether the educators could make an accurate estimate of which mistakes were most common. We find that educators’ estimates do not agree with one another or the student data, and discuss the implications of these results.

Frame-Based Editing

In introductory programming teaching, block-based editors have become very popular because they offer a number of strong advantages for beginning programmers: They avoid many syntax errors, can display all available instructions for visual selection and encourage experimentation with little requirement for recall. Among proficient programmers, however, text-based systems are strongly preferred due to several usability and productivity advantages for expert users. In this paper, we provide a comprehensive introduction to a novel editing paradigm, frame-based editing – including design, implementation, experimentation and analysis. We describe how the design of this paradigm combines many advantages of block-based and text-based systems, then we present and discuss an implementation of such a system for a new Java-like language called Stride, including the results of several evaluation studies. The resulting editing system has clear advantages for both novices and expert programmers: It improves program representation and error avoidance for beginners and can speed up program manipulation for experts. Stride can also serve as an ideal stepping stone from block-based to text-based languages in an educational context.

The Cost of Syntax and How to Avoid It: Text versus Frame-Based Editing

Plain text has always been the predominant medium for writing and editing programs for expert users. Text is powerful and flexible, but requires more careful manipulation than structural editors, such as those found in block-based environments. In addition, in textual editors programmers are responsible for managing detailed orthography and layout - when beginners work with text, significant time is spent managing syntax problems, indentation and spacing. Frame-based editing is a new editing paradigm that combines the structural editing of block-based systems with the flexibility and keyboard-focus of text editing. In this paper, we empirically examine how much time and effort is spent by beginners on managing syntax errors and indentation, which can be automatically saved by switching to frame-based editing. The data is obtained using the Blackbox dataset, the results predict a clear advantage of frame-based editing over traditional text editors.

Greenroom: a teacher community for collaborative resource development

Developing and sharing teaching material is a significant challenge for users and developers of novel teaching tools and techniques. The Greenroom is a community web site for teachers using the Greenfoot software that provides a novel design to overcome various problems associated with sharing resources and supporting teachers. The Greenroom is of immediate interest for Greenfoot teachers, but also for designers of similar teacher community sites.