Designing practical work to reduce cognitive load and increase learning

By Heather King - June 2011


Scharfenberg, F.-J. & Bogner, F. X. (2010). Instructional efficiency of changing cognitive load in an out-of-school laboratory. International Journal of Science Education, 32(6), 829–844.

The authors claim that if the students are given an overdose of information, their memories become ‘overloaded’; for example, engaging in an activity in a professional science laboratory. To counter this negative impact, the study here suggests ways to lessen the ‘cognitive overload’ and inform instructional design.

Cognitive load can be thought of as the amount of new information that an individual can hold at any one point. Until we fully understand something, we rely on our working memory to retain a relatively small number of pieces or ‘chunks’ of information. Too much information leads to cognitive overload. The nature of the information or cognitive load is divided into the intrinsic ‘load’ of the topic in hand (that is, the new content), the extraneous ‘load’ which refers to the instructional approach, and germane ‘load’ which describes the ability to make sense of the new information and transfer it into long-term memory. The components are additive, and thus as Scharfenberg and Bogner point out, ‘reducing intrinsic and/or extraneous load may have the potential to increase the germane component, which is of prime importance for learning’ (p. 831).

To study the effects of reducing intrinsic and extraneous load in the context of an out-of-school lab-based session, the authors compared two groups of 12th grade students engaged in a study of marker genes in bacteria. This included the transformation of bacteria using a recombinant plasmid; isolation of the transformed plasmid; restriction analysis of the plasmid using three enzymes; and visualisation of results using gel electrophoresis. The first group participated in the conventional lab session. The second treatment group took part in a modified session, which included four additional phases of focussed discussion of about 5 minutes each, in between each step of the experimental process. The intention here was to help the treatment students consolidate the new information they had encountered during the prior activity by way of discussion and introduce the next set of processes. The authors hypothesized that this system would help students to concentrate on their performance of the task rather than focussing on recalling all the experimental processes for the full procedure, which would contribute to a considerable extraneous load.

For their analysis of the impact, the authors assessed the students’ knowledge gain by pre- and post- and delayed post tests, and measured their mental effort and task performance at various stages during the daylong session. In summary, the treatment group were found to show a lower level of effort in the final interpretation phase of the activity and to perform cognitively better in the long term (as shown by a test after six weeks). The authors argue that the treatment approach of breaking down the activity and introducing opportunities for recap and discussion may have prevented students’ cognitive overload, and thus promoted deeper learning.

The authors conclude that the findings point to the advantages of teaching practical science by simply adding short focussed discussions that both focus students’ attention and serve to introduce the new set of experimental steps. They note that this finding applies for instructors of out-of-school lab-based sessions as well as to teachers planning practical work in schools.

The authors acknowledge that the long-term achievement effect is similar to that found in other studies where students engage in discussions in an amicable atmosphere. However, such studies have rarely been interpreted in terms of cognitive load.