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Distillates - Chemical Education


Distillates
David Read looks at some recent chemical education research.


More effective practical work for A-level chemistry


Chemistry equipment

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For most A-level chemistry students, practical work involves 'following a recipe' in what are known as expository activities. This is also the case in many university labs, although in recent years there has been a shift towards a 'problem-based learning' (PBL) approach for at least part of the practical programme in many institutions. The reported benefits of PBL include the development of transferrable skills such as team-working and communication, as well as improved independent learning. In her role as an RSC school teacher fellow, Catherine Smith has developed and evaluated a suite of PBL practical investigations to support A-level chemistry teaching.

A total of 10 activities have been developed, all accompanied by pre-lab exercises and appropriate support materials to help students tackle the problem. Each activity is based on a 'real world' context, and is intended to deepen students' understanding of the laboratory techniques involved. The activities are designed to support different parts of the syllabus so they can be run over the span of a two year course. This article outlines the rationale behind the approach and describes a trial that involved over 100 students in 8 different schools. Pre- and post-activity questionnaires were used to probe the students' views of expository and PBL practical activities, producing some interesting outcomes.

Independent learning is a key concern, especially for students going on to university study. Smith's activities have been designed to give students the opportunity to decode information, use different sources, recognise where help is needed, and the ability to see that making mistakes is a vital ingredient of learning. The evidence documented in the article shows that, for some students at least, these sorts of activities actually do have an impact on students' independence and their ability to think for themselves.

Whenever students are taken out of their comfort zone, there is a risk that they will withdraw due to their fear of the unknown, and this manifested itself during the trial. A sizable minority of students, including some of the most able students, indicated that they were uncomfortable with the PBL activities. However, the overall impact of the new activities was positive for both students and teachers. In particular, the lack of direct instructions was cited by many to be a good thing, with the indication that this led to enhanced understanding. Teachers reported that students were motivated by the activities and that they enjoyed the 'meaty' challenges provided. The fact that they also suggested that they were now planning more open-ended tasks shows the high regard they had for the new approach, which will hopefully give others the confidence to try them in their own classrooms.

References

C Smith, Chem. Educ. Res. Pract.,  2012, 33, 490  (DOI: 10.1039/C2RP20096A[Ed - All 10 practical activities can be downloaded from the RSC website.] 


Related Links

Link icon Problem-based practical activities
A collection of 10 practical activities where students apply their understanding of a concept to devise a solution to a 'real-life' scenario


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How well do exams probe scientific understanding?


Students sitting an exam

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Many observers have expressed concern in recent years that excessive testing and the over-reliance of the authorities on the results of national tests in judging teaching standards and school performance has been harmful to teaching and learning. Furthermore, many students at all levels of academic ability fail to demonstrate their potential in terms of exam results, and the arguments about how best to assess performance are ongoing. In a US study, Noble et al  have investigated the correlation between students' conceptual understanding and their ability to answer exam questions correctly. 

While the study focuses on grade 5 science tests, any teacher whose students are regularly sitting exams will be interested in the outcomes. Most teachers will have students in their classes who clearly have a good grasp of the underlying scientific principles behind a particular concept, but are then unable to produce the appropriate response to gain the marks on an exam. The aim of this study was to determine whether the knowledge and skills that students report using to answer questions are the same as those that the questions intended to test. Students completed a six question science test which was followed by an interview that probed their actual level of understanding of the concept. This produced some interesting results, particularly when students from different social groups were compared. 

A total of 36 students were involved in the study. 12 students came from low income households, 12 students were 'English Language Learners' (ELLs) and the remaining 12 students were native English speakers (NES) largely from middle-class backgrounds. The authors first considered the students who had demonstrated a good understanding of a question's target knowledge in their interview. They found that low income students and ELLs were more likely than NES students to have given an incorrect answer in the exam when they actually had a good grasp of the concept being tested. When they considered students who did not demonstrate a grasp of a question's target knowledge, the authors found that NES students were considerably more likely to still submit a correct answer than those from the other groups. 

The investigation indicated that the use of language in the text of the questions was the main issue affecting the performance of low-income students and ELLs. This comparative disadvantage was compounded by the high incidence of NES students who were able to give correct answers despite having a poor understanding of the concept, which raises serious questions regarding the use of such exams to measure attainment. The authors conclude with the suggestion that alternative measures of scientific knowledge that are responsive to students' backgrounds and experience are essential to allow all of them to demonstrate their true abilities, a suggestion which will ring true for many educators in different countries across the globe. 

References

T Noble et alJ. Res. Sci. Teach., 2012, 49, 778 (DOI: 10.1002/tea.21026