Pupils’ conceptual difficulties: electricity Electrical misconceptions

Some of the earliest work on learners‟ misconceptions was carried out by Driver, et al. (1985) and Driver, Squires, et al. (1994). This section begins by considering Shipstone (1984) and Shipstone (1985) which reported pupils‟ likely misconceptions about electricity. Later work by Shipstone, et al. (1988) considered older pupils‟ difficulties learning about electricity in five European countries. Shipstone et al. found that although there were some differences among learners in different

countries, there were common areas of difficulty, which could be combined to form a coherent picture of pupil difficulties. The pupils‟ coherent, but incorrect picture agreed with the findings of Shipstone‟s earlier research. Pupils believed that the battery supplied a constant current, which was influenced locally rather than globally by circuit components. Components were believed to consume current, rather than loosely speaking “consuming” energy. This belief may have arisen because the pupils did not distinguish correctly between current and voltage. Duit, Jung and von Rhoeneck (1985) edited the proceedings of a 1984 conference about teaching

electricity which included discussion about many of these issues. Similar results were later reported for university students, Picciarelli, Gennaro, Stella, & Conte (1991).

An alternative approach to investigating pupil‟s conceptual difficulties was used by Pine, Messer, & John (2001), who asked experienced primary teachers to identify topics pupils found more difficult. Electricity was one of the areas the teachers identified.

Electricity

Around the same time as Driver, et al. (1985) were investigating pupils‟ conceptual difficulties across a range of science topics, Duit et al. (1985) edited the book of a conference which discussed pupils‟ difficulties learning electricity. More than a decade later Duit & von Rhöneck (1998) reported similar findings about the

possible way to help pupils to learn about electricity more successfully, Mulhall et al. (2001) identified a number of problems for pupils learning about electricity.

According to Mulhall et al. (2001, p. 580):

… there are not even the beginnings of any form of justified

consensus about the range and nature of models/analogies/metaphors that might be appropriate for the teaching of electricity at any given level or at different levels.

They went on to argue that the basic concepts of electricity are not clearly defined in many textbooks. The next three subsections explore pupils‟ likely knowledge about direct current, voltage and resistance which are the three basic electrical concepts included in Table 3.2 above.

Direct current

Exploring the final version of the Students' and Teachers' Conceptions and Science Education (STCSE) database, Duit (2009), revealed that most references to teaching one specific aspect of electricity were about direct current.

Stocklmayer & Treagust (1996) considered how novices and experts modelled direct current as did Borges & Gilbert (1999). Both sets of authors found progression in learners‟ ideas about current as they gained in experience and both found pupils‟ models did not agree with expert models.

Voltage or potential difference

In contrast with direct current, the STCSE database contained many fewer references containing only the words “voltage” or “potential difference”. This may be because the traditional emphasis on teaching introductory electricity is on direct current rather than voltage. According to Psillos, Koumaras, & Tiberghien (1988, p. 29) in their introduction of voltage as the main concept in teaching electricity,

The learning of this concept [voltage] is considered as very difficult.

The meaning of voltage in electrical circuits is not well-understood by many learners. Part of the problem may be that potential difference and electromotive force (emf) may be treated as synonyms for voltage, although the three concepts have related but different meanings, as discussed by Page (1977).

Millar & King (1993) and Millar & Beh (1993) discussed the problems 15-year old pupils had understanding voltage in simple series and parallel circuits. They concluded that many pupils struggled to answer qualitative questions about a simple series circuit and used local rather than global reasoning, as reported by other

authors. Similarly, when discussing pupils‟ understanding of parallel circuits, pupils again used an incorrect approach by considering the problem as being to do with adding resistors in parallel rather than voltage in parallel and applied V = IR incorrectly.

Liégeois, Chasseigne, Papin, & Mullet (2003) reported that pupils tended to ignore information about resistance because they considered voltage and current to be similar concepts. This made it difficult for the pupils to include information about resistance when trying to calculate potential difference.

In this section about voltage and the previous section about direct current, authors have argued for the use of current or voltage as the primary concept when

introducing pupils to electricity. However, Silva & Soares (2007) have argued that rather than arguing for current or voltage as the primary concept, it is better to concentrate on the electric circuit as a system where the current and the voltage interact with and influence each other.

Resistance

The number of authors who dealt mainly with teaching and learning resistance was limited, perhaps because current and voltage were seen as the main explanatory concepts for teaching electricity. Liégeois and Mullet (2002) discussed the lack of

studies about learners‟ understanding of resistance. In their study, they highlighted learners‟ lack of understanding of the concept of resistance and also the lack of impact of teaching about resistance. Liégeois and Mullet‟s research was supported by aspects of Shipstone‟s (1984 and 1985) earlier work about children‟s

understanding of electrical concepts including resistance.

Cheng & Shipstone (2003a) introduced the concept of an AVOW (amps, volts, ohms and watts) diagram as a possible approach to teaching about these concepts. Despite reporting positive effects when using AVOW diagrams with A-level learners and their teachers, Cheng & Shipstone (2003b), this approach does not seem to have been taken up more widely.

As part of her doctoral research, Engelhardt developed a test to assess understanding of basic concepts in current electricity, including resistance (Engelhardt and

Beichner, 2004). However, the focus seemed to be on current and voltage rather than resistance.

Despite the documented difficulties learners have with the concept of resistance, the Standard Grade physics syllabus, SQA (2004e, p. 29), treated the concept of

resistance as straightforward. Once the concept had been defined, it was then used in other content statements. A similar approach was taken in the approach to resistance in the arrangements documents for the Intermediate 1 and 2 physics courses, which were developed after the Standard Grade physics course.

Conceptual understanding movement

Much of the work discussed above was carried out by interview or observation with school pupils in primary or early secondary schools. However, the conceptual understanding movement, beginning with the Forces Concept Inventory, Hestenes, Wells, & Swackhamer (1992a), surveyed the understanding of American high school or university students about a range of topics. For example, Maloney, O'Kuma, Hieggelke, & Van Heuvelen (2001) and Ding, Chabay, Sherwood, & Beichner

magnetism. However, both the Maloney, et al. (2001) and the Ding, et al. (2006) surveys were at too high a conceptual level to investigate the understanding of basic school electricity.

Engelhardt & Beichner (2004) produced a diagnostic test to investigate pupils‟ understanding of direct current resistive electrical circuits. The test was called “the Determining and Interpreting Resistive Electric Circuit Concepts Test”, otherwise known as DIRECT. This test is suitable to investigate pupils‟ understanding of basic electrical circuits. Version 1.0 is available in the public domain, but version 1.2 which is not in the public domain was obtained through information on the NCSU Physics Education R & D Group (2007) “Assessment Instrument Information Page.”

As argued in the earlier parts of this section, teaching electricity to pupils is difficult. Mulhall, et al. (2001) argued that electricity is a difficult topic for pupils to learn because the content is very abstract and consists entirely of models. Additionally, there was no agreement among teachers about what should be taught at different levels. A possible solution to the first part of Mulhall et al.‟s approach may have been offered by Cheng & Shipstone (2003a), who developed a diagrammatic approach to teaching about electricity holistically at post-16 level. Their approach has been trialled in schools with some success, Cheng & Shipstone (2003b). However, this approach does not seem to have been more widely adopted.