Nuffield Curriculum Centre

Science issues

Contexts or concepts: which should lead in post-16 Science?
Author: Sarah Codrington

Contexts act as a motivating ‘bridge’ for learning the related science concepts in context-led advanced science courses such as Salters Advanced Chemistry, Salters-Horners Advanced Physics and Salters-Nuffield Advanced Biology. In more conventional concept-led courses, applications and contexts are used to illustrate the science rather than being the central framework for the curriculum.

A session at the January 08 Association for Science Education annual conference explored both sides of the debate. Here are summaries of what each speaker said, and of the debate which followed.

Michael Reiss, Professor of Science Education at the Institute of Education, University of London, Director of Education at the Royal Society and Salters-Nuffield Advanced Biology Director chaired the debate. Michael opened by pointing out that while there has been a rise in curriculum development projects which start with contexts, the majority of students still take concept-led courses.

John Holman, National Science Learning Centre Director and National STEM Director, was the original project Director of Salters Advanced Chemistry (SAC). John said that in this course the topics start with contexts such as ‘The Atmosphere’ and ‘Developing Fuels’, and the chemical principles are in a separate book. The aim is high student attainment and engagement. A study by Vanessa Kind, presently at the University of Durham, showed no difference between students’ understanding of chemical concepts such as bond energy after SAC and traditional courses; and teachers reported that the contexts were effective in engaging student interest and helping them to think about job prospects. John Holman reported that he had asked 150 undergraduate chemistry and biochemistry students at the University of York in 2007 why they were motivated to continue their study; the most important influences were their teacher and the job prospects, ahead of the course and the textbooks. A drawback of concept-led courses is that they may not have the same tidy logic for the students as they do for their teachers: the structure corresponds with the teacher’s understanding but not necessarily the students’.

Jon Ogborn was Nuffield Advanced Physics and IoP Advancing Physics project Director, and Professor of Science Education at the Institute of Education. Jon said Advancing Physics is both concept- and context-led. In developing a course, he would draw on a list of concepts. But scientific knowledge is not made of such a list. How to deliver these concepts? It took about 20 years for teachers to get the concepts into their heads, so it is not surprising that they aren’t in the students’ heads. Day-to-day teaching is about how to get the students involved, and how to organise this – contexts can help. But a concept-led approach can also involve students and give them a good idea of the shape of the subject (see 30 years of Nuffield Advanced Physics). Jon said he doubts whether teachers can effectively use the same contexts year after year when it’s the concept rather than the application which is the real reason for teaching, and when applications may be hard to grasp and may become less relevant as time goes on. However Advancing Physics does use some contexts, such as teaching electric circuits via sensors, but sensors continue to be an integral part of the physics course. Jon favours the use of explanations rather than concepts as organising units for the curriculum. It means that a science course consists of explanations and stories about how things work, coming from how things are. Some are about how useful things work, and some are about the inner workings of nature. Both deserve a place.

Nicola Wilberforce teaches Salters-Nuffield Advanced Biology (SNAB) at Esher College. The contexts provide a starting-point for a study of the concepts, and students gain a more rounded understanding. For instance, students are introduced to proteins as molecules which have to be a particular shape in order to do a particular job transporting substances across membranes. Then they learn about enzymes, and subsequently they have few problems linking this concept to the role of proteins as neurotransmitters, receptors, hormones and transcription factors etc. As the college has an open access policy, students with quite low GCSE grades often began A-level biology but were quickly disillusioned with the biochemistry and detailed cell biology with which conventional courses start. Students now say that the context-led approach makes more sense, and attainment and retention rates have improved markedly since the adoption of SNAB.

John Apsey teaches Chemistry at Hazelwick School Crawley, a mixed 11-18 comprehensive school; he is currently Chief Examiner for Nuffield Advanced Chemistry, and future Chair of Examiners for Edexcel Advanced Chemistry. The starting-point for these courses is the intellectual appeal to students of developing their understanding of concepts. A-level chemistry students tend to go into medicine or other biological sciences, engineering or into industry, and the concepts in the course are chosen with this in mind. When York chemistry undergraduates were asked ‘in what ways did your A-level course let you down?’ they referred to the lack of development of practical skills rather than not enough maths or not enough about applications. John gave an example of the development of the concept of energy throughout an A-level course, including practical work as well as contexts where appropriate. This could start with test-tube experiments on thermal decomposition to give students the chance to develop their observational skills. Exothermic and endothermic reactions could then be explored using 'hot and cold compresses' as sporting examples. This would lead on to Hess's Law, and the use of combustion experiments to enable enthalpy changes which could not be measured directly to be calculated. These experiments are an ideal place to discuss relative errors and to practise drawing graphs. The context of types of fuel could be used as examples. Activation energy and bond energies can then be introduced as well as entropy to explain why endothermic reactions may occur and exothermic ones may not. How industry can influence the rate of reactions and the position of equilibrium together with relating the equilibrium constant, electrode potentials, and total entropy change, completes the A-level journey on the concept of energy in an intellectually satisfactory way.

The debate
Here are some points made in discussion.

Mary Ratcliffe, Professor of Science Education at Southampton University, asked whether context-led assessment helps to show students’ understanding, or does it just get in the way? But if all assessment is concept-led, teachers are unlikely to use contexts in their teaching. Jon Ogborn suggested that Paul Black would say that contexts make assessment items more difficult; however, contexts are used in assessment of Advancing Physics; concepts are tools for thinking, contexts are a way of setting up arguments and explanations and installing concept packages in students’ heads. Liz Swinbank, Salters-Horners Advanced Physics Director, said that contexts are used in assessment to test students’ abilities to apply concepts in new situations. One of those present, who described himself as a SNAB convert, said that he uses contexts when teaching and concepts when students are revising. Nicola Wilberforce said that she thinks that the extraction of concepts from contexts is part of revision.

Chemistry concepts are intellectually difficult, and need to be explained several times. John Holman said that we need to think ourselves into the heads of students in order to explain effectively, starting with what students have learnt so far rather than with what makes sense to the teacher (constructivism). David Barlex, Nuffield Design & Technology Director, said that students should be encouraged to explain concepts with their teacher’s help, so as to avoid the transmission model. Angela Hall, Nuffield Curriculum Centre Director and SNAB Director, said that Biology does not fit into neat conceptual areas.

Michael Reiss and Jon Ogborn said that students are very different from each other; some prefer a context-led approach while others prefer beginning with the concepts. For example, some student find the proof that there is an infinite number of primes or that the square root of two is irrational very beautiful. Other students prefer to learn about prime numbers via the context of internet security. Some students are excited by the theory of quantum physics, and starting with applications is not helpful to them. John Holman asked whether there are gender differences in student preferences. Nicola Wilberforce said that at Esher College it is more frequently the girls from single-sex schools who are frustrated by contexts, and just want to be told what to learn. However Nicola says this is exactly why the context-led SNAB course is so good as it forces them to think. Jon Ogborn said that this applies to boys too.

Summary
John Holman said that we tie down teachers too much with prescriptive schemes of work and assessment – we should liberate teachers to think for themselves.

John Apsey said it is important that assessment enables teachers to use practical work, ideas about how science works, and contexts in their teaching.

Nicola Wilberforce said that SNAB produces more rounded scientists, students with a more holistic way of thinking.

Jon Ogborn said he thinks that the success of SNAB is the result of thinking very hard about what is really important in science, rather than the context-led approach.

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