Teaching the DC Electricity Unit of the Physics Enhancement Course

This post describes my teaching of the course planned in an earlier post, and as such demonstrates an example of my meeting dimension A2 of the UK PSF. It also shows my understanding of how students learn in this context (K3) and an ability to design appropriate methods for teaching postgraduate pre-ITT students about DC Electricity (K2).

Learning Activities

Teaching began with a group discussion on the topic “What is electricity?”, the purpose being to ascertain prior understanding to enable personalised instruction and differentiated teaching later in the unit. This approach has had positive responses from students in previous studies (e.g. Windschitl, 1999). The discussion lead into a more didactic ‘lecture-style’ presentation of foundation concepts using slides of notes, images, and visual animations, alongside practical demonstrations (such as the use of a van der Graaff generator to support understanding of the ‘threshold concept’ of electrical charge).

The content-led didactic portions of sessions were interspersed with simple activities to increase student engagement. An example of this was ‘code-cracking’ to determine the value of a resistor from the coloured bands printed upon it. Whilst this may seem trivial it emphasised the range of values and tolerances available, familiarised students with the resistor as an electrical component, gave a chance to demonstrate problem-solving skills, and the subsequent experimental confirmation allowed experience of hands-on testing of components.

The importance of practical work in studying science subjects has been emphasised in many studies, (see Woodley, 2009; Dillon, 2008; and Abrahams & Millar, 2008). Whilst some practical activities included in this unit of the PEC were somewhat basic, differentiation was used to ensure all students were engaged and learning. An example of this was testing materials to see if they are electrical conductors or insulators. Although this is a primary school level activity, some less experienced students were given a method to follow and the aim of familiarising themselves with equipment, whilst students with more of a background in the subject were encouraged to take a problem-based learning approach, and use patterns, measurements, and additional independent research to attempt to relate their findings to the atomic structure of the materials in question.

In other practical activities students took the lead on learning. A particularly successful example of this approach was making fruit batteries. The initial activity was to see which fruit produced the greatest potential difference, but students set themselves the extension task of seeing how many grapes would be required to charge a mobile phone. At this point they allocated group roles depending upon expertise; those with more mathematical confidence carried out calculations and made predictions, whilst those still getting to grips with equipment put mathematical predictions to the test. This not only shows a level of ownership but also embodies a sort of active learning that has shown positive results in studies (see for example the metasynthesis of Prince, 2004).

Figure 1: The use of the quiz module as a subject knowledge audit.
Figure 1: PEC students making fruit batteries

Each day finished with some small-group examination-style questions to strengthen connections between the theory covered in the session and the prescribed content, which has been shown to greatly aid retention, far more than standard ‘revision’ (Karpicke & Roediger, 2008). Content was re-visited at the start of the following day through a series of ‘quick-fire’ activities involving anagrams, quizzes, and puzzles based around definitions.

A significant portion of the unit (and indeed Physics) is mathematical in nature, so it is essential to embed numerical skills development (the importance of mathematical skills in HE has been recognised by the HEA – see Croft & Grove, 2006).

Familiarity with manipulating equations was promoted by the use of a range of questions of increasing difficulty. Students were encouraged to get as far as possible in a fixed time, with a use of classroom timers to give a sense of pace. This is one use of use of Assessment for Learning (Black & Wiliam, 1990) to give a ‘baseline’ level of mathematical ability which could be subsequently used to inform future activities and groupings in later sessions.

The approach to embedding mathematical skills during practical work was usually twofold. First, students made experimental measurements and plotted a graph. Clear success criteria for plotting were given in advance, and one-to-one support provided. Practical results were then algebraically checked against theory. Students worked in pairs or small groups, and I ensured that those most familiar with mathematical techniques were paired with students without such a strong background. This type of peer support has been shown to be effective by studies such as Parkinson (2009).

Subject pedagogical knowledge

Discussing the pedagogy of DC Electricity as it applies to high-school teaching is easy to embed in the PEC; an approach that asks questions along the lines of “we are carrying out some learning activities that are appropriate for the topic. How might you implement them in a school setting? What difficulties might you face? What might school pupils find difficult? Or interesting?” serves as a suitable starting point.

The van der Graaff demonstration is an excellent example of this, as not only can one emphasise the variety of learning opportunities in the demonstration, but also highlight the health and safety implications of such equipment in schools, referencing not only practitioner literature (e.g. SSERC, 2007), but also personal anecdotes from my experiences of teaching this topic.

Assessment and Misconceptions

Alongside the taught portion of the DC Electricity unit students were given time to construct a portfolio which A) demonstrated and documented what they had learnt, and B) would allow them to easily access this learning on subsequent courses. Part A received significant continuous formative feedback during session contact time, and was made up of results of experiments, exam questions, and class-based written tasks. Part B was assessed summatively, and was more like a personalised textbook of notes and teaching materials.

Given that role of the PEC is to provide a background knowledge for students to take into their initial teacher training courses, it seems logical that a large proportion of the formal assessment is by portfolio. Segers et al. (2008) also suggest that adopting ‘assessment tasks as an integrated part of the learning environment… resulted in enhanced performance’ (p. 43).

A major strength of such continuous assessment was the prompt identification of misconceptions. One example of this is understanding the ‘threshold concept’ of current and voltage, ideas that are frequently confused. After an initial discussion of the topic highlighted some misconceptions, I employed the use of two analogies; a some school buses, and a series of water pipes. As a group we discussed the strengths an shortcomings of analogy, and students were encouraged to think of own – a task that not only shows understanding, but also serves and aid to memory (Halpern et al., 1990). As such students were better able to articulate the different concepts of current and voltage.

Outcomes and Evaluation

Whilst it is beyond the scope of this post to formally evaluate the unit, and results of a end-of-course student survey are presented in another post, some brief observations can be made.

The first is the excellent work produced for portfolios, which I believe show a suitable assessment model and a high level of engagement. The mixed and differentiated approach to learning also seemed successful, with students informally reporting that they found the sessions informative, useful, and enjoyable.

I was, however, surprised by the by level of preference for ‘hands-on’ practical work; the demonstration with the van der Graaff generator was not so well received, especially in comparison with playing with fruit batteries. It seems that even postgraduates enjoy getting their hands dirty!

The final observation I would make was that three continuous days of relentless DC electricity was perhaps a little exhausting (for students and tutors alike!). There was also a little replication of learning with some practical tasks being too similar. Next year I will cut the content into more discrete chunks, and trim down the quantity of practical exercises.

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References

Abrahams, I., and Millar, R. (2008) ‘Does Practical Work Really Work? A study of the effectiveness of practical work as a teaching and learning method in school science’. International Journal of Science Education 30(14), pp. 1945-1969.

Black, P., and Wiliam, D. (1990) Inside the Black Box: Raising Standards Through Classroom Assessment. London: GL Assessment Limited/Kings College London.

Croft, T., and Grove, M. (2006) ‘Mathematics Support: Support for the specialist mathematician and the more able student’. MSOR Connections 6(2)

Dillon, J. (2008) A Review of the Research on Practical Work in School Science. London: King’s College London.

Halpern, D. F., Hansen, C., and Riefer, D. (1990) ‘Analogies as an aid to understanding and memory’. Journal of Educational Psychology 82(2), pp. 298-305.

Karpicke, J. D., and Roediger, H. L. (2008) ‘The Critical Importance of Retrieval for Learning’. Science 319(5865), pp. 966-968.

Parkinson, M. (2009) ‘The effect of peer assisted learning support (PALS) on performance in mathematics and chemistry’. Innovations in Education and Teaching International 46(4), pp. 381-392.

Prince, M. (2004) ‘Does Active Learning Work? A Review of the Research’. Journal of Engineering Education 93(3), pp. 223-231.

Segers, M., Gijbels, D., and Thurlings, M. (2008) ‘The relationship between students’ perceptions of portfolio assessment practice and their approaches to learning’. Educational Studies 34(1), pp. 35-44.

SSERC, Scottish Schools Education Research Centre (2007) Van de Graaff generator hazards. Edinburgh:(no. 223)

Windschitl, M. (1999) ‘Using Small-Group Discussions in Science Lectures: A Study of Two Professors’. College Teaching 47(1), pp. 23-27.

Woodley, E. (2009) ‘Practical work in school science – why is it important?’. School Science Review 91(335), pp. 49-51.