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Asia-Pacific Forum on Science Learning and Teaching, Volume 21, Issue 1, Article 7 (Dec., 2021) |
In this section, the findings are presented with two sub-headings according to the research questions. Accordingly, in the first part the distribution of the electric field exam questions of the lecturer according to PCK taxonomy and in the second part the distribution of the answers given by the pre-service science teachers to these questions according to their level of understanding and the change in the success of the pre-service science teachers according to PCK taxonomy are presented.
Types of questions preferred in written assessments about electric field
The distribution of the written exam questions, which include 12 questions about electric field concept, according to the categories of familiar procedures-PK1, complex procedures-PK2, conceptual understanding-CK1, conceptual applying CK2 and procedural and conceptual knowledge integration PCK is presented below (Table 2).
Table II. Distribution of written exam questions according to PCK taxonomy
PK1
PK2
CK1
CK2
Q3; Q4
Q8; Q12
Q1; Q2; Q6; Q10
Q5; Q7; Q9; Q11
Table II shows that the lecturer included questions related to different categories of the PCK, although the highest number of questions (8 in total) was related to conceptual learning (4 questions in the CK1 category and 4 questions in the CK2 category). 2 of the remaining 4 questions are in the category of Familiar procedures (PK1) and the other two are in the category of Complex procedures (PK2) and there are no questions in the category of Procedural and conceptual knowledge integration (PCK).
PK1, familiar procedures: questions on writing the electric field units and the rules in drawing the field lines are categorized as PK1.
Q3. Write the units of electric field.
Q4. Write the rules of drawing electric field line.
PK2, complex procedures: Questions requiring the use of rich procedural knowledge are included in category PK2. The first of these questions, Q8, requires mathematical expression for the ratio of distances d1/d2 as seen in the Figure 1 M being the point where the electric field is zero. The second question, Q12, asks to determine the directions of motion of charges K, L and M, seen in the Figure 2.
Q8. What is the ratio d1/d2 given that the resultant electric filed at point M produced by charges q1 and q2 is zero?
Figure 1
Q12. What will be directions of the charges K, L and M, when they are released? 1 or 2?
K:
L:
M:
Figure 2
CK1, conceptual understanding: The four questions in the category CK1 are about defining the electric field, explaining the sources of the electric field, determining the amount and type of charge using electric field lines in Figure 3, and determining the signs of electric charges depending on the drawn field, Figure 4.
Q.1.Write the definition of the electric field.
Q.2. What is the general source of electric fields?
Q6. Determine the kind and amount of charges producing the electric field shown in the Figure 3.
Figure 3
Q10. .Electric field lines produced by tree equal point charges 1, 2 and 3 placed along the vertical line are as drawn in the Figure 4. Write the signs (+, -) of charges
1 ….. ; 2 ….. ; 3 …..
Figure 4
CK2, conceptual applying: It is seen that there are four questions in category CK2 and these are related to the use of electric field lines and the drawing of the electric field vector for unusual positions. Questions in this category are listed below.
Q.5. Can you suggest a common test to determine whether or not an electric field is present at a point in space?
Q.7. Draw the electric field vectors at the points X and Y in Figure 5.
Figure 5
Q.9. Six charge distributions are given on the Figure 6. Draw on the same figures the electric field lines produced by these distributions.
Figure 6
Q.11. Two equipotential lines around a positive point charge are shown in the Figure 7 Draw the electric field vectors at points a, b and c.
Figure 7
It can be said that the questions in this category require the application of more than one conceptual situation related to general detection of the electric field at a point, drawing the electric field vectors, showing the electric field lines for different charge distributions, and drawing the electric field vectors at three different points on an equipotential line around a positive charge.
Students' Level of Understanding
The distribution of the answers given by the pre-service science teachers to the exam questions according to their levels of understanding is presented in Graph 1.
Graph 1. Distribution of pre-service science teachers’ answers according to their levels of understanding
When the distribution of the answers given by the pre-service science teachers to the questions on the electric field according to their level of understanding is examined, it is seen that this distribution differs depending on the PCK category.
Graph 1 shows that the number of answers at the level [3] in the CK1 category is higher than those in the other categories. It is seen that the numbers of answers given at the level [3] in the categories PK1 and PK2 are close to each other, and most of the answers not consistent with scientific knowledge are in the category PK1
The least answers at the level [2] are in the category CK1, and the distributions of answers in the other categories are similar to each other. It is also seen that the answers incompatible with scientific knowledge, at level [1] are concentrated in the categories PK2, then in PK1, CK1 and CK2 The greatest number of irrelevant answers and blanks at the level [0] take place, in the categories CK2, then PK1, PK2 and CK1. It is seen that more than half of the pre-service science teachers answered the question Q3 on the units of electric field at level [1] in the category PK1, while the other answers are distributed equally at the levels [3] and [0] and being no answer at level [2]. Pre-service science teachers mostly answered the question on drawing rules of the electric field, Q4, respectively at levels [2], [3], [1] and [0]. Answers to the question asking mathematical expression for the ratio of the distances from the two charges to the zero-field point, Q8 in category PK2, are concentrated at level [1], while the remaining answers are distributed at levels [3] and [0] with similar ratios. Answers to question Q12 also in the category PK2 and asking to the directions of motion of charges are mostly at level [3] and then at levels [2], [1], [0] respectively.
The answers to three of the four questions in category CK1 (Q2, Q6, and Q10) are most often at level [3], indicating that they are compatible with scientific facts, while the answers to the fourth question, Q1, on the definition of the electric field, are at level [1].
It was seen that the answers given to the questions in category CK2 about proving the presence of the electric field, Q5 and drawing the electric field lines for various charge distributions, Q9, are concentrated at level [3]. The remaining answers for Q5 are at levels [0] and [1] with similar ratios and the remaining answers for Q9 are essentially at level [2]. It is remarkable that the answers given to the questions asking to draw the electric vector at a point on a field line, Q7, and drawing the electric vectors at some points on the equipotential circle with a positive charge at its centre, Q11, are mostly at levels [0] and [1]. In addition to the distribution of the pre-service science teachers’ answers according to different levels of understanding, Graph 2 shows the average score of each pre-service science teachers’ answers to the questions in the categories PK and CK.
Graph 2. The average scores due to answers to questions in the categories PK and CK.
The average scores of the participants are presented in Graph 2, which reveals that a large significant part of the pre-service science teachers (38 out of 59) obtained higher scores in the conceptual understanding than in the procedural understanding category. The scores of remaining 17 pre-service science teachers in the category of procedural understanding are higher than the scores in the category of conceptual understanding while four participants got similar scores in these two categories.
