Total recall: Research shows how a novel pedagogy incorporating ‘pre-labs’ can aid retention of knowledge from practical work over time

The experimental nature of chemistry means that teaching needs to help develop students’ investigative and practical skills. How this can be best done, however, remains a subject of debate. The UK tradition of school students engaging in practical work goes back to 1904, when it was first mandated by the Board of Education. Since the introduction of GCSE examinations in 1988, which are taken by most UK students at age 16, there have been numerous changes to requirements for the assessment of practical work, the latest iteration commencing teaching in 2016.

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Recalling knowledge from practicals over time is essential for GCSE students

Under the current GCSE system, there is no direct assessment of students’ practical skills – schools are required to confirm, without evidence, that students have undertaken and recorded practical work based on a minimum of eight practical activities specified by the awarding body. Instead, practical skills are assessed indirectly by allocating of 15% of the marks on written exams to questions based on those specified practicals. With exams taking place at the end of year 11, approaches that help students retain knowledge and understanding of practical work they undertook perhaps a year or more previously are highly desirable. In this study, Hennah shows that this can be achieved using a novel pedagogy which incorporates pre-laboratory activities.

The article presents a review of the literature around instruction for practical work, referring in particular to the problems with ‘recipe’-style practicals based on what are often complicated written instructions: these can overload working memory and lead to students taking a ‘mind-in-neutral’ approach. It also draws on previous research which suggests that incorporating pre-laboratory resources helps reduce students’ cognitive load during practical activities, which supports the assimilation of learning. Such ‘pre-labs’ are now widespread in university teaching, and this study outlines an approach for deploying them at school level.

The novel pedagogy was designed around a titration practical and began with a demonstration video that outlined the process for the technique step by step. After watching the video, students completed a pre-lab question sheet featuring images from the video as visual prompts; this helped to link the abstract concept in the question to the practical procedure itself. These visual prompt slides in place of written instructions are a significant feature of this pedagogy, and they were used in class to stimulate verbal discussion: the prompt slide poses key questions, the answers to which helped students to use their own thinking to implement the technique correctly, rather than simply ‘following the recipe’. Students were provided with a worksheet to scaffold the data collection and titration calculation processes; this drew on the pre-lab tasks and helped them to link their practical experience to the work they did beforehand. They were also given a peer observation form, enabling them to give feedback to each other.

… may indeed aid students in retaining their learning from practical activities over a period of time, which will help them in their GCSE examinations

The article discusses a broad range of data, but the key finding was based around the performance of one class of students (n=31) on two different practical activities: crystallisation was taught ‘traditionally’, while neutralisation was taught using the alternative pedagogy outlined above. Ten weeks after completing each practical activity, students completed an unannounced test; the results showed that they performed significantly better in the test based on the neutralisation task. This suggests that the novel pedagogy may indeed aid students in retaining their learning from practical activities over a period of time, which will help them in their GCSE examinations.

It should be noted that this research was carried out by a practising teacher working in a state school – such activity isn’t the preserve of universities. By empowering more teachers to engage in this kind of research, we will be able collect more data, from which we can draw robust conclusions and drive an evidence-informed revolution in our approach to teaching.

Teaching tips

This approach could be applied to all practical techniques. The teaching materials are freely available for download with the article, and they can be used to develop similar resources as required.

  • Many videos are available online outlining practical techniques that can be used in pre-labs, but you can also use a smartphone to make your own videos featuring the same equipment that your students will use in their own classroom setting.
  • Abandoning the ‘recipe’ sheet approach can be quite a wrench, but there is ample evidence that visual prompts used in this way are highly effective, and the use of questions and discussion resulted in students carrying out the procedure correctly. It is important to manage the discussion in class, and perhaps train students in how to approach the questions in order to tease out the correct technique.
  • As noted, this work draws on relevant areas of cognitive science, which is an area of growing interest in science education. If you wish to learn more, you might consider signing up to the #CogSciSci mailing list.