Student teachers’ levels of understanding and model of understanding about Newton's laws of motion

The findings from the achievement test are presented using the headings students’ level of understanding and students’ model of understanding.

A. Students’ level of understanding

The findings from the achievement test are presented below after analysing each item about Newton’s Laws of Motion.

Table 4 Percentages of Responses to Questions – Level of Understanding

	*First Law of Motion*				*Second Law of Motion*				*Third Law of Motion*
Levels	A	B	C	D	A	B	C	D	A	B	C	D
[0] NR	-	18	2	38	2	47	49	42	9	13	11	16
[1] NU	2	4	-	6	-	6	6	6	9	11	20	2
[2] IU	16	29	33	6	24	6	11	-	11	2	16	-
[3] PU	-	4	4	23	4	4	4	36	6	2	2	42
[4] SU	82	44	60	27	69	36	29	16	64	71	51	40

Levels of Understanding: [0] No response; [1] No Understanding; [2] Incorrect Understanding; [3] Partial Understanding; [4] Sound Understanding

Students’ level of understanding about Newton's First Law of Motion (Law of Inertia)

Table 4 shows that all students answered the “explaining the sample case” question. Most of the answers (82%) were classified at the sound understanding level. The remaining responses were classified as incorrect understanding (16%) and no understanding (2%). However, only 44% of student responses about the question asking with "which law the sample case could be explained" were classified as sound understanding (level 4), while there were also significant numbers of incorrect understanding (29%) and partial understanding (18%) responses. The analysis of the levels in the first two questions showed that although the students knew that the car’s matter had the tendency to move forward in the result of a car’s sudden brake, they were not aware that this situation could be theoretically explained with the law of inertia.

Table 4 also shows that responses to the third question, requiring students to write a sample case about the Law of Inertia, were mainly classified as sound understanding (60%) and incorrect understanding (33%). There were no responses at the no understanding level and only a few responses at the partial understanding (4%) and no response (2%) levels. The percents of the levels for this question show that most of the students could give a similar event as an example by analyzing the sample event given in the first question. Sample answers given below show clearly the students’ implication:

Suppose that we are running down a slope. Even we try to stop immediately we cannot (Student 8).

Water spills forward when we immediately stop while we are walking with a glass of in our hands (Student 25).

An eraser on a book tries to keep its position when we draw the book away fast (Student 41).

Victims in cars collided head-on rush forward (Student 31).

These answers were classified at the sound understanding level. However, a student answer classified at the incorrect understanding level was: A flying bird hits against the wall (Student 44).

Half the responses to the final question asking for a definition of the Law of Inertia were classified at the no response (38%), no understanding (6%) and incorrect understanding (6%) levels. However, 23% of responses were classified as partial understanding and 27% were classified as sound understanding. The percentage range among levels and the decline in the students’ achievement can be correlated with the levels of achievements in item B. Because an important number of the students can’t state correctly the law of physics expected in item B, the general achievement in this question has fallen according to the other questions. Thus it can be said that only a small part of the students that could state the related law couldn’t correctly explain the law of inertia. Below are examples of some of the responses that were classified as insufficient and incorrect understanding:

The law of inertia is defined as the product of all the forces applied on an object body (Student 8).

Inertia is that stable objects (trees, traffic lamps etc.) seem as if they were moving, while we are traveling on a bus (Student 14).

Students’ level of understanding about Newton's Second Law

Table 4 shows that 69% of students gave sound understanding level responses for explaining the sample case question about Newton’s Second Law of Motion. However, this percentage was much lower for the other three questions (36%, 29% and 16% respectively). The students’ achievement in the first question probably results from the fact that they have been expected to reason about the given situation rather than to make an explanation about the theoretical knowledge. This also explains that the students’ general achievement has fallen progressively. Accordingly, whereas the students succeeded in the question related to procedural learning, they couldn’t reach to the same success in the questions related to the conceptual learning.

When the responses to the first question about the second law were examined in detail, it was found that 69% of students gave scientific explanations and were classified at the sound understanding level (see Table 4). Most of the other responses for this question were classified at the incorrect understanding level (24%), with very few classified at the partial understanding level (4%) and no response level (2%).

The question that asked students to determine the physics law explaining the sample case shows that 47% of student responses were classified at the no response level. Answers classified at the sound understanding level (36%) were higher at than the remaining levels of no understanding (6%), incorrect understanding (6%) and partial understanding (4%).

Responses for the question requiring students to write a sample case that could be used to explain the second law of motion were classified as insufficient to a large extent. The responses to this question were mostly placed in the first three categories (no response, 49%; no understanding, 6%; and incorrect understanding, 11%). Examples of the no understanding responses were:

The reaction of a dropped pen when it hits the floor (Student 10).

Cars stopping at different velocities (Student 30).

The remaining 29% of responses were classified at the sound understanding level, while 4% were classified at the partial understanding level.

Forty two percent of responses to the final question about Newton’s Second Law of Motion were classified at the no response level. The remaining responses were classified at the partial understanding (36%), sound understanding (16%) and no understanding (6%) levels.

Students’ level of understanding about Newton's Third Law

Responses to the four questions about Newton’s Third Law of Motion were better than those for the other laws of motion. They were mainly at the sound understanding level (item A, 64%; item B, 71%; item C, 51%; and item D 40%). Students’ achievement can be related to the simplicity of remembering the related law; because according to Newton's third law ‘for every action, there is an equal and opposite reaction’. Besides, events explained by this law can be experienced in real life (for example, when we hit the wall, etc.), and these events increase the achievements level of understanding in the questions related to this law.

Table 4 shows that most of the responses explaining a sample case question about the Third Law of Motion were classified as sound understanding (64%) and partial understanding (6%) levels. However, there were 9% for no response, 9% for no understanding and 11% for incorrect understanding categories.

Seventy-one percent of responses to the question about determining the physics law explaining the sample case in the first question were at the sound understanding level. Nevertheless, there were 13% at the no response level and 11% at the no understanding level, while 2% were classified as incorrect understandings and 2% were classified as partial understandings.

Additionally, half the responses to writing a sample case for Newton’s Third Law were classified at the sound understanding level. The no understanding level was 20%, the incorrect understanding level was 16% and the no response level was 11%, with 2% of responses classified at the partial understanding level. Examples of responses classified at the sound understanding and partial understanding levels were:

The backward movement of the body when someone kicks the wall (Student 1).

The backward reaction movement of arms when we hit sledgehammer on a stone (Student 23).

Backward shake when someone is putting the shot (Student 4).

A student’s pulling his hand as soon as the teacher hits his hand with a stick (Student 9).

Forty two percent of responses asking for a definition of Newton’s Third Law of Motion were classified as partial understanding with forty percent classified at the sound understanding level. Sixteen percent of the remaining responses were classified as no response and 2% as no understanding.

B. Students’ model of understanding

To determine the Model of Understanding students used the main characteristics of responses were matched to the characteristics shown in Table 3. The resulting classifications are shown in Table 5.

Table 5 Percentage of Responses to Questions- Models of Understanding

Model of Understanding	First Law of Motion	Second Law of Motion	Third Law of Motion
Optimum Model	31	22	40
Uncreative Model	7	16	16
Theoretical Model	-	4	9
Practical Model	31	11	11
Memorizing Model	2	2	13
Inappropriate Model	18	34	7
Others	11	11	4

Table 5 shows that the students’ achievement changes according to the understanding models. According to that, Optimum Model appears more in the Third Law of Motion and appears less in the second Law of Motion. That is, an important part of the participants don’t have the expected scientific knowledge related to the second Law of Motion. This situation is supported with the percentage observed in the inappropriate model in the second Law of Motion. Recall that optimum model includes the knowledge nearest to the scientific knowledge, while inappropriate model includes the farthest knowledge.

Determining the model of understanding proved difficult for some students. Consequently, they were placed in the “others category”. When responses from students placed in the others category were investigated, it was found that the majority of them answered the first two questions about one of Newton’s laws then did not answer the remaining questions about that law.

Students’ Model of Understanding about Newton's First Law of Motion (Law of Inertia)

When responses for each of the four questions about Newton’s First Law of Motion were analyzed, it was found that 31% of the students used the optimum model while a further 31% used the practical model. This means that one-third of students gave acceptable answers for all questions, and another one third could apply knowledge effectively, but could not explain the theoretical bases of this knowledge. When optimum model is correlated with conceptual learning and practical model with procedural learning, it can be said that all students having optimum model have succeeded in all questions and the students having practical model have succeeded only in the questions involving practical using of knowledge as in the procedural learning. However, 18% of students were classified as using an inappropriate model, while 7% used the uncreative model and 2% used the memorizing model. No student used the theoretical model.

Students’ Model of Understanding about Newton's Second Law of Motion

When responses for each of the four questions about Newton’s Second Law of Motion were analyzed, the inappropriate model dominated. Thirty-four percent of students could not provide appropriate responses to any of the questions asked about this law. The situation related with this law, which is also known as the basic principle of dynamics, is very interesting. The fact that inappropriate model is the most appearing one is due in particular to the fact that Newton’s Second Law of Motion is generally related to theoretical knowledge rather than to applications in daily life. Although this law is used to explain many physical phenomena, it doesn’t enter the students’ life like other laws, and it is not correlated with the interesting events.

However, 22% of students used the optimum model and were able to respond appropriately to all questions asked about this law. It was also found that 16% of students could not write a sample case for this law and were classified in the uncreative model category, while 11% of students used the practical model. Only one student, (2%) used the memorizing model and 4% used the theoretical model.

Students’ Model of Understanding about Newton's Third Law of Motion

When responses for each of the four questions about Newton’s Third Law of Motion were analyzed, it was found that more students gave appropriate answers to questions about this law than for the other two laws, with 40% of students classified in the Optimum Model category. Sixteen percent of students gave appropriate answers to the other questions except the one asking them to writing a sample case explained by the Third Law and so were classified in the uncreative model category. The proportion of students using the memorizing model was 13%, the practical model was 11% and the theoretical model was 9%. Additionally, the number of the students using an inappropriate model for Newton’s Third Law was relatively low at 7%.