Development and use of one-dimensional models of a golf ball

One-dimensional models of a golf ball are useful in modelling near-normal (90 degrees) impact. The model described here has two masses connected by a non-linear spring in parallel with a non-linear damper. The behaviour of this system in collision with an infinite rigid mass is compared with the results of tests involving real golf balls. Values of the four unknown constants are found by fitting the model results, over a range of impact speeds from zero to 50 m x s(-1), to the coefficient of restitution and duration of contact found in the tests. The simplest model (Model 1) was a good fit for duration of contact over the whole range of impact speeds, but for the coefficient of restitution only at high speed (above 20 m x s(-1)). However, when used with a similar model of a flexible faced club, the simple model predicted the coefficient of restitution of the club-ball combination, determined by direct testing, quite well and as such is a useful screening tool. More complicated Models 2 and 3 fitted the rigid target coefficients of restitution better at low speed than Model 1. However, Models 2 and 3 have other disadvantages and are no better than Model 1 for high-speed impact with flexible faced clubs.     

There is no such thing as a product

How do you manage, or even think seriously about, profitability in an online business? Traditionally you tracked profitability by product, but in the online world this may simply not be possible. The article looks at why this is so, and how the same factors which create the problem also create new opportunities.     

Widening the gap? The challenges for equitable music education in Scotland

Exposure to and potential to engage in music is now very different for children and young people from more middle-class and affluent backgrounds compared to those from working-class or poor households. Middle-class children and young people have access to opportunities to learn an instrument and engage in performance, predominantly for intrinsic reward and on occasion as the basis of a future career. Children and young people from more working class or poor backgrounds are more likely to be excluded from these opportunities and are less likely to take advantage of opportunities within the wider world of music industries. This research draws on in depth case studies of three local authorities in Scotland to reveal the ways in which local provision for music education is largely being reshaped by economic factors and restraints. Drawing on aspects of critical theory it discusses the ways in which economic-based decisions are interacting with the dominant social and cultural values to influence provision. It makes the argument that in an era of austerity the social and cultural values of the middle class are dominant and effectively increasing inequality in access to music. Children and young people from poor or working class households are increasingly excluded from opportunities to engage with formal music provision.     

Computer-Supported Argument Maps as a Policy Memory

This article investigates to what extent computer-supported argument visualization can be designed to encourage debate and deliberation by citizens on public issues. Such argument maps use icons and arrows to represent the structure of a series of related viewpoints, reducing the amount of text necessary to convey the ideas, thereby clarifying the issue under consideration. Argument maps have the potential to provide a readily accessible medium by which citizens can follow and join in public debates on policy issues. In this article we describe our approach and the type of maps we have chosen to use and then demonstrate the potential of a collection of maps to form a “policy memory” to support policy development. Our case study is the development of the “smoking in public places” policy in the Scottish Parliament. Our overall aim is to engage citizens in democratic decision making, leading to better policymaking and a more engaged citizenry.     

The Support Model for interactive assessment

The two most common models for assessment involve measuring how well students perform on a task (the quality model), and how difficult a task students can succeed on (the difficulty model). By exploiting the interactive potential of computers we may be able to use a third model: measuring how much help a student needs to complete a task. We assume that every student can complete it, but some need more support than others. This kind of tailored support will give students a positive experience of assessment, and a learning experience, while allowing us to differentiate them by ability. The computer can offer several kinds of support, such as help with understanding a question, hints on the meanings of key concepts, and examples or analogies. A further type of support has particular importance for test validity: the computer can probe students for a deeper explanation than they have so far given. In subjects like geography or science, markers often would like to ask ‘yes, but why?’, suspecting that students understand more than they have written. We describe a series of studies in which students were given a high level task as an oral interview and then as an interactive computerised assessment with varying types of support. Implications of the support model for future modes of assessment are discussed.     

The method of Adaptive Comparative Judgement

Adaptive Comparative Judgement (ACJ) is a modification of Thurstone’s method of comparative judgement that exploits the power of adaptivity, but in scoring rather than testing. Professional judgement by teachers replaces the marking of tests; a judge is asked to compare the work of two students and simply to decide which of them is the better. From many such comparisons a measurement scale is created showing the relative quality of students’ work; this can then be referenced in familiar ways to generate test results. The judges are asked only to make a valid decision about quality, yet ACJ achieves extremely high levels of reliability, often considerably higher than practicable operational marking can achieve. It therefore offers a radical alternative to the pursuit of reliability through detailed marking schemes. ACJ is clearly appropriate for performances like writing or art, and for complex portfolios or reports, but may be useful in other contexts too. ACJ offers a new way to involve all teachers in summative as well as formative assessment. The model provides strong statistical control to ensure quality assessment for individual students. This paper describes the theoretical basis of ACJ, and illustrates it with outcomes from some of our trials.