From theory to practicals – what does cognitive science suggest for teaching practical science?

Adam Stubbs, Teacher of Science and Maths, Evidence Leader in Education, Park View School, UK

With the move to integrate cognitive scienceThe study of the human mind, such as the processes of though... More research into classrooms, there has been a focus on tangible aspects of learning such as knowledge. Discussions surrounding retention, retrieval and cognitive load often focus on knowledge-based components of learning, occasionally ignoring the application of them to the development of skills such as practical science. Given the importance of practical science in developing skills, attitudes and vocational outcomes, as well as considering the fact that in most schools practical activities occur in the majority of lessons (Gatsby, 2017), there is a significant opportunity to improve technical outcomes by engaging with research. 

A number of key cognitive concepts can be applied to the practical science classroom. Firstly, novices conceptualise tasks differently from experts (Chi et al., 1979). This applies to practical activities as much as theoretical ones. For example, when a student sees a beaker with liquid inside, the teacher sees an acid, as well as their entire well-developed schema that accompanies this: how acids react, concentration, safety and practical considerations, such as ensuring that colourless liquids are clearly labelled and not placed on the edge of a table. Students run the risk of not realising how much they don’t know. This can delay learning and cause significant safety risks. When a student undertakes a practical, there are competing cognitive processes to juggle. Students need to be able to understand the instructions as well as to use equipment correctly and safely; this is known as procedural knowledge. They also need to relate this to the subject knowledge being studied – the conceptual knowledge. In even the most seemingly simple practical tasks, this can quickly overwhelm their working memory, as large components of their schemas are missing (Tsaparlis, 2009). 

As teachers, our role is to support students to manage this new information in such a way that they can learn something useful and relevant. There are a number of strategies rooted in cognitive science that can help students to manage this new information.

The purpose of practicals

With the possibility of such high cognitive demand, it is worth firstly asking whether a practical activity is necessary. If the aim is to demonstrate a practical concept or technique, then using a whole-class demonstration instead of a practical would allow the teacher to more effectively control the pace of explanations and steps, and to manage cognitive demand throughout (Boxer, 2021a). This is why many practicals are more suited to whole-class demonstrations. However, if the aim is to create a ‘buzz’ or act as a hook, then this can act as a ‘seductive detail’, which can reduce subsequent learning because pupils focus on the wow-factor to the detriment of the lesson objective. Moving a demonstration to the end of a lesson can reduce this effect as it prevents students from thinking about the seductive details during the core part of the lesson, whilst still allowing the teacher to later showcase them (Alexander, 2019). Using unusual practical’s to engage students with surprising or unexpected results can also cause problems, as the cognitive conflict caused can lose students in the underlying complexity, and result in more confused misconceptions (Baddock and Bucat, 2008).

If the aim is to support students to perform practicals, then a practical would be necessary; if the aim is to use practical methods to teach theory, then inquiry-based learning is a poor method with which to develop scientific understanding, as it is likely to overwhelm students’ working memory, so don’t expect them to turn into budding little Marie Curies straightaway (Driver, 1993; Kirschner et al., 2006; Millar and Abrahams, 2008).

Pre-teaching

A student’s working memory is fundamentally limited, and there are many aspects of a practical task that can result in cognitive overload. If they are overwhelmed with new concepts, apparatus and techniques, then it becomes difficult for them to successfully perform each step, and even more challenging to grasp the conceptual purpose of the practical. One approach to minimise this is pre-teaching key concepts and techniques in advance. This could involve delivering practicals at the end of a topic instead of the start, so that students are familiar with the theory first, rather than beginning with an inquiry-based practical, which is more likely to overload learners (Kirschner et al., 2006). Another approach pre-teaches techniques in advance of the practical. For example, if a practical activity has multiple steps, these can be broken down and taught in advance. Pre-teaching students how to flute a filter paper in advance of a filtration practical will reduce the number of new techniques to which students are exposed in the practical, reducing cognitive load. 

A similar approach uses flipped learning to deliver key instructions in advance of a practical task. Instead of giving students a set of instructions with zero preparation, try providing students with the practical steps in advance of the lesson. Flipped learning is an effective way in which to expose students to the techniques in advance, and can be maximised by providing students with a video demonstration and prerequisite quiz on the apparatus, techniques and safety precautions. This approach is used more widely in university teaching and can be applied to support sixth-form students to develop good practical study habits (Stieff et al., 2018). 

Isolating practical skills

Isolating skills by breaking down practicals can allow the development of individual skills without requiring the overload of a full practical. Take an introductory Year 7 science practical such as investigating the effect of salt on the boiling point of water. In theory, the practical is simple: measure the boiling point of water, then add salt and repeat to see whether the boiling point changes. But in practice, this one practical contains a raft of potentially new skills for a student to tackle. In one practical lesson, these could include: using a Bunsen burner, using a measuring cylinder, weighing out an accurate mass of salt, measuring temperature, handling boiling liquids, safely tidying and cleaning apparatus, recording data, types of variables and completing a practical write-up. Each individual step has its own challenges, so together they can provide a high level of challenge for novice students. 

One analogy to support students is that of a good driving instructor. Like science teachers, a driving instructor’s number one priority is managing safety at all times. Expert instructors wouldn’t ask a complete novice to drive on a motorway in their first lesson; they isolate key skills such as clutch control, lane positioning and observations, and only then combine these when students demonstrate success. By managing cognitive load in this way, students are able to focus on the most important parts of each step and develop each skill in isolation. 

Applying this analogy to a practical lab, expecting students to manage complicated, multi-step activities filled with hazards that they haven’t performed before is asking for trouble. Instead, break the practical down into key skills to focus on over time. During one practical lesson, isolate the skill of correctly using a Bunsen burner, focusing entirely on hazards and how to light and use it safely. In another lesson, isolate the skill of measuring and challenge students to measure set volumes of salt and liquids as accurately as possible. Another lesson could focus on designing and recording tables, with a final lesson learning about practical write-ups. This has the benefit of reducing the number of tasks that students are expected to perform at once, reducing the range of possible risks and allowing the teacher to assess performance and provide feedback more precisely. 

Managing practical steps 

When guiding pupils through practicals, managing the speed at which they move through each step matters too. Breaking down larger tasks and providing opportunities to discuss the purpose and rationale of each step can reduce the number of steps that students must undertake, and allow them to focus on understanding the practical purpose of each step (Scharfenberg and Bogner, 2010). One effective approach is the ‘slow practical’, which explicitly guides pupils through each step at a time, with clear modelling throughout, instead of providing a written method and asking students to work through every step at their own pace. The more explicitly and each step is explained and modelled, the more likely it is that pupils will correctly perform them (Boxer, 2021b). This is effectively providing students with a model of cognitive apprenticeship (Collins et al., 1991).

The format of instructions also affects how effectively students can perform tasks. Written instructions can generate a split-attention effect, whereby attention is split between the paper and the physical demand of the task. For example, the instruction ‘Using the burette, titrate approximately 15cm3 of sulfuric acid into the ammonia’ requires students to convert the text into a physical step. If they are unfamiliar with any words, then it becomes almost impossible to perform. If the bottle of ammonia is labelled using its chemical formula NH3 instead of its name, then this presents a further barrier. This split-attention effect can be reduced through the use of integrated instructions that include visual diagrams to reduce cognitive load (Paterson, 2019; Haslam and Hamilton, 2009).

Spacing practical skills

Once a practical has been performed, the principle of spacing can be used to distribute opportunities to recall and perform this across the curriculum. Using the principle of isolation, we can then isolate practical methods (such as steps to make a pure, dry salt) from key procedural techniques (working with Bunsen burners and measuring liquids) and then space these across the curriculum. Students don’t need to perform entire practicals multiple times, but by isolating key steps we can embed them collectively within a pupil’s schema. For example, the steps in making a pure, dry salt can be reviewed in starter questions and homework across the year, without needing to return to a whole-class practical. However, the procedural techniques can be practised throughout the curriculum in other practical activities that use similar apparatus. By retrieving procedures over time, practical and conceptual understanding can be strengthened (Hartman et al., 2022). Within a curriculum, a number of core practical competencies can be identified. These can then be mapped out over time and spaced throughout the curriculum. Ideally, core competencies, such as using a Bunsen burner safely, should be spaced out across a key stage to enable procedural techniques to be revisited and practised over time.

Good theory is good practice

Most importantly, the same techniques used in good teaching apply equally well to practical science. The principles of effective instruction apply as well to practical teaching as they do to conceptual teaching, something that good PE teachers know well. The techniques of regular review and retrieval, introducing new information in small steps and modelling are all vital for effective practical teaching, be it science, PE or drama (Rosenshine, 2010). For example, when teaching students how to improve the accuracy of a forehand shot in tennis, their technique will improve more with 10 minutes of practice for 10 sessions than with 100 minutes of continuous practice. The trick when teaching practical science is to apply these ideas to the science lab. Choosing purposeful practicals, pre-teaching, isolating and managing each step all prevent unnecessary cognitive overload. The strategy of spacing can then be used to retain the competencies over time and to turn practical science into a carefully considered, well-sequenced and essential part of the curriculum.