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Asia-Pacific Forum on Science Learning and Teaching, Volume 13, Issue 1, Article 5 (Jun., 2012) |
As a result of the analysis, a total of 50 analogies were identified in high school physics textbooks. Each analogy was examined independently by two faculty members who are researchers and experts on physics education. In the process of analogy classification, the rate of 94.9% consensus was achieved for 350 classifications (7 criteria x 50 analogies). As a result of discussion, a consensus was achieved for the remaining 18 classifications (5.1% of 350 classifications). An average of 12.5 analogies was found in each book. It was seen that the fewest analogies (8) were in book A, and the most (16) were in book C (Table 1). According to previous studies, there is an average of 8.3 analogies in elementary and high school science textbooks in the United States (Curtis & Reigeluth, 1984), an average of 9.3 analogies in high school chemistry textbooks in Australia (Thiele & Treagust, 1994), an average of 43.5 analogies in high school biology textbooks in Australia (Thiele et al., 1995), an average of 2.6 analogies in elementary school science textbooks in the UK (Newton, 2003), an average 19.75 analogies in college bio-chemistry textbooks (Orgill & Bodner, 2006), and an average of 17 analogies in biology textbooks in Turkey (Dikmenli, 2010).
In terms of the analogical relationship between the analogue and target concepts, it was identified that functional (48%) and then structural-functional (30%) and structural (22%) analogies were most commonly used in physics textbooks (Table 1). Functional analogies are often used to understand difficult and abstract physics concepts and they are also of an engaging nature. For example, “as soon as the tap is opened in the compound containers the water flows right through from the container where the water level is high to the one with less water. This flow will continue until the water levels in the two containers are equalized. The reason for the water flow is due to the difference in the water level of the containers. If the level of water is synchronized there is no water flow… So must there be a difference between the water levels that is similar to the one between the poles of the battery? Can the difference in water levels be likenend to the potential difference between the poles of the battery, causing the movement of electrons to start in electrical circuits? This difference between the poles of the battery is defined as potential (voltage). The current will continue to pass through the circuit until this difference is reset. If there is no potential difference between the poles of the battery the current does not go through from the circuit the battery it is connected to” (Book A, p. 185).
Table 1. Categorization and number of analogies in secondary school physics textbooks
Books
A
B
C
D
Total number of analogies
Category
Number of analogies
8
13
16
13
50
%
Analogical
Relationship
Structural
1
2
6
2
11
22
Functional
4
7
7
6
24
48
Structural-Functional
3
4
3
5
15
30
Presentational
Format
Verbal
4
7
13
11
35
70
Pictorial-Verbal
4
6
3
2
15
30
Condition of
Subject Matter
Concrete- Concrete
1
1
1
3
6
12
Abstract-Abstract
3
5
2
1
11
22
Concrete-Abstract
4
7
13
9
33
66
Position in Text
Advance Organiser
1
1
-
1
3
6
Embedded Activator
7
12
14
12
45
90
Post Synthesiser
-
-
2
-
2
4
Level of
Enrichment
Simple
5
5
12
7
29
58
Enriched
3
4
4
3
14
28
Extended
-
4
-
3
7
14
Pre-Topic
Orientation
Analogue Explanation
2
1
-
1
4
8
Strategy Identification
3
3
5
5
16
32
Both
1
2
1
3
7
14
None
2
7
10
4
23
46
Limitations
Existing
-
1
2
-
3
6
None
8
12
14
13
47
94
An example of a structural-functional analogy used in textbooks is: "Reflection and transmission of light waves is similar to the movement of spring waves. That is, a thin spring in a soft breaker environment acts like a thick spring in a very hard breaker atmosphere" Book D, p. 95). An example of a structural analogy used in textbooks is: "... the atom radius is about 10-10 meters. Positive loads are distributed evenly into the sphere. Negative loads are sorted to make the atom neutral and their locations are fixed. This model is also called a ‘raisin cake model’ as it looks like raisin cakes" (Book D, p.122). This is explained in the structural analogy by comparing the structure of an atom to a raisin cake. According to previous research, multi-functional analogies have mostly been used in chemistry textbooks (Thiele & Treagust, 1994), biology textbooks (Thiele et al., 1995) and college bio-chemistry textbooks (Orgill & Bodner, 2006). When considering whether functional or structural-functional analogies are more effective in education (Duit, 1991; Thiele & Treagust, 1994), understanding is required of the circumstances in which such analogies are frequently encountered in physics textbooks. In a structural analogy, students are supposed to know that the analogue and target concepts only share structural features. Otherwise, students may transfer the function and behavioural features from the analogue towards the target (Orgill & Bodner, 2006).
In terms of the presentational format of analogies in the book, it has been discovered that the analogies presented were 70% verbal and 30% pictorial-verbal (Table 1). One of the analogies presented in pictorial-verbal format established similarities between atoms and the solar system. "In the atomic model developed by Rutherford, the positive charge in the atom forms most of the mass and has a centre named the nucleus. Electrons in the spaces outside the core revolve around the nucleus like the planets in the solar system" (Figure 2) (Book C, pp. 221-222).
Figure 2. Image of an analogue in a pictorial-verbal analogy (Book C, p. 222).
In this analogy, the text is supported by a picture of the analogue (solar system) and thus the structure of the atom is made attractive and permanent to students. Another example of pictorial-verbal analogies used in textbooks is: "Expansion of the universe after the big bang can be compared to the inflation of a balloon" (Figure 3) (Book C, p. 342).
Pictorial-verbal analogies are found in the books examined in previous studies (Dikmenli & Kıray 2007; Orgill & Bodner, 2006; Thiele et al., 1995). Thiele et al. (1995) reported that only 6 of 174 analogies in four high school biology textbooks were presented using a pictorial-verbal format. It is important to support analogical texts with pictures to make the analogies interesting for students because pictures are always interesting. However, this is particularly important for elementary and high school students. Pictorial-verbal analogies are easier to remember and increase the permanence of knowledge. It is known that pictures are more memorable than sentences. Bean et al. (1990) reached the conclusion that an analogy presented in a pictorial-verbal format is more effective in understanding the structure and functions of a cell than an analogy presented in verbal format.
Figure 3. Image of an analogue in a pictorial-verbal analogy (Book C, p. 342).
In terms of the condition of the subject matter it was found that to present the analogue and target concepts, 66% of the analogies in books are concrete-abstract, 22% concrete-abstract and 12% abstract-concrete (Table 1). The use of more concrete-abstract analogies in physics textbooks in Turkey is natural and desirable because the most important role of analogies in teaching is to make the target concepts in abstract properties concrete for the learner. The best style of teaching goes from concrete to abstract. An example of the concrete-abstract analogy type in the textbooks used is as follows: "... collision of photons with electrons is similar to the collision of two billiard balls" (Book D, p. 107). These findings are similar to the findings of previous studies (Curtis & Reigeluth, 1984; Orgill & Bodner, 2006; Thiele et al., 1995). However, Newton (2003) in his study, stated that the concrete-concrete analogy type was used more often (59.8%) in science textbooks written for the 7-11 age-group students of elementary schools. The researcher reported that this case is connected with the cognitive level of younger age-group children.
In terms of the position of the analogue relative to the target, the embedded activator analogy is most common in physics textbooks (90%), then respectively (6%) advance organiser and (4%) post synthesiser analogies have been used (Table 1). Similar results were revealed in previous studies (Curtis & Reigeluth, 1984; Orgill & Bodner, 2006; Thiele & Treagust, 1994). Newton (2003) noted that all the analogies in science textbooks prepared for 7-11 age-group students in the UK were presented as embedded activators. Embedded activator types of analogies are more intuitive for students. Advance organiser or post synthesiser types of analogies require more experience and prior knowledge for the student.
In terms of the level of enrichment, simple (58%), and then respectively, enriched (28%) and extended (14%) analogies are used in physics textbooks (Table 1). Roughly similar rates have been revealed in other studies (Dikmenli & Kıray, 2007; Dikmenli, 2010, Thiele and Treagust, 1994; Thiele et al., 1995). However, detailed analogies will help students transfer new information to old information (Paris & Glynn, 2004). Studies indicate some dangers with simple analogies. In simple analogies, students must establish the relationship between the analogue and target on their own. Therefore, the use of simple analogies may also often cause students to develop wrong concepts (Thiele et al., 1995). Glynn and Takahashi (1998) stated that analogies must be explained clearly or enriched for the purpose. It has been found that detailed analogies make students learn the target concept and increase their interest (Paris & Glynn, 2004).
In terms of pre-topic orientation, just 8% of analogies used in physics textbooks used analogue description only, 32% strategy definition only, and 14% used both strategy definition and description of the analogue. In 46% of analogies neither a description of the analogue nor any definition of the strategy was found (Table 1). It is important to explain the basic properties of the analogue used in an analogy to enable an analogical transfer to be correctly established between the analogue and target. Description of the analogue and definition of the strategy both help to direct students to focus on suitable features for the analogical transfer (Thiele & Treagust, 1994).
In terms of limitations of analogies, limitations were pointed out in 6% of the analogies used in physics textbooks, while there was no emphasis on the limitations in 94% of the analogies (Table 1). An example that points to the limitations of analogies used in textbooks is as follows: "... naming the movement of electrons as electric current, we have compared the electron movement to the water flow that occurred when we opened the tap which tied the containers with different water levels to each other. In this case, it is the level differences that make the water move. This level difference is explained as potential difference. We have compard the water molecules to electrons. In this figuring, we need to note that the movement of electrons cannot simulate exactly the movement of water molecules... " (Book B, p.141). It is necessary to specify the breaking points that may cause misunderstandings in the analogies used in books or unshared features between the analogue and target to prevent false concepts arising from the analogies (Brown & Clement, 1989; Clement, 1993; Coll & Treagust, 2001).
