Knowledge of Student Learning Difficulties as a Plausible Conceptual Change Pathway Between Content Knowledge and Pedagogical Content Knowledge

Abstract

There is a collective agreement about the necessity of content knowledge (CK) as a prerequisite for pedagogical content knowledge (PCK). However, most PCK models lack explanatory power because of the missing link between CK and PCK. Thus, the study firstly attempts to develop a theoretical model that consists of knowledge of students’ learning difficulty (KSLD) as a plausible pathway between CK and PCK with the conceptual change research entry. Secondly, it tests the causative relationship between CK and KSLD of PCK. The CK for this study constitutes acid rain, as well as the concepts of photosynthesis and cellular respiration. Seventy-three preservice science teachers (PSTs) participated in this study. The study used open-ended surveys and vignette-based individual interviews to measure PSTs’ CK and KSLD, respectively. The results indicate that (1) PSTs’ CK and KSLD are low. (2) There is a significant correlation (p < 0.01) between PSTs’ CK and KSLD. (3) Compared with a low or moderate level, the high level of PSTs’ CK is a significant predictor (p < 0.01) of their KSLD. Qualitative evidence supports preliminary quantitative results of the study. The study provides a PCK model that indicates KSLD as a plausible pathway to connect CK and PCK, using a conceptual change inquiry as a point of entry. The study implies the proposed PCK model based on conceptual change learning is useful for future teachers in responding to student learning difficulties. Besides, the PCK model is a fertile ground for robust research.

Appendices

Appendix 1. Some questions of the CK surveys

• How do natural and man-made sources contribute to acid rain? Please describe the pathway of acid rain.

• What are the effects of acid rain on ecosystems, including soil, forests, streams, and lakes?

• What are the consequences of acid rain on human health and materials?

• What should be done to reduce or prevent acid rain? Give reasons.

• Describe the processes of photosynthesis and cellular respiration. Explain the related concepts.

• Why is photosynthesis important to all life on earth?

• Explain the factors that affect the rate and efficiency of photosynthesis?

Appendix 2. Examples of science vignettes used for individual interviews with the PSTs

Appendix 3. The PCK-level continuum as degrees of understanding (naive, transitional/mixed, and informed—0/1/3.5)

Informed view (3.5 points): The PSTs responded appropriately to each open-ended question in the CK surveys. They identified all students’ learning difficulties as well as their rationale based on each vignette during the interview.

Transitional/mixed view (1 point): The PSTs responded but not entirely appropriate for each open-ended question in the CK surveys. The PSTs identified some of the students’ learning difficulties in each vignette, without supporting the rationale of the learning difficulties during the interview.

Naive view (0 points): The PSTs’ answer to each open-ended question in the CK surveys expressed a view that is neither appropriate nor plausible. It means that PSTs’ views are inconsistent with the scientifically acceptable ideas. The PSTs identified neither students’ learning difficulties in each vignette nor any supportive rationale during the interview.

Appendix 4. Grouping PSTs into high, moderate, and low achievement groups according to their CK and KSLD

High achievement group: PSTs in the high achievement group should have a total score between 13.5 and 21 from CK surveys and between 9 and 14 for the vignette-based interview of each topic. It means that the PSTs must have the scientific view for at least three of the six CK questions and two of the four vignettes. Also, they should have a partial view of the remaining parts or appropriate answers to more than three of the six questions of each content survey, and two vignettes of the interview on each topic.

Moderate achievement group: PSTs in the moderate achievement group should have a total score between 3.5 and 12.5 for each CK survey and between 3 and 8 for the vignette-based interview of each topic. It means that the PSTs must have a partial scientific view of at least half of the six CK questions and the four vignettes, including the appropriate, plausible, and naive views for the remaining parts of each content survey and each interview.

Low achievement group: PSTs in the low achievement group should have a total score between 0 and 3 for each CK survey and between 0 and 2 for the vignette-based interview of each topic. It means that the PSTs must have a partial scientific view of the three of the six CK questions and two of the four vignettes at most. These include the naive views of the survey’s remaining parts or no appropriate answer for each content in the survey and each interview on each topic.

Note: We used statistical analyses to test the differences among the three levels of understandings of the CK and the KSLD. For both types of knowledge (i.e., CK and KSLD), the PSTs in the high achievement group were significantly better (p < 0.01) than the PSTs in the moderate and low achievement groups. Similarly, the significant difference (p < 0.01) favors PSTs in the moderate achievement group compared with the PSTs in the low achievement group for both CK and KSLD. The claim then is that this approach is valid for the study to answer the second and third research questions.

Appendix 5. An example of the interview excerpt based on vignette 2 on “plant nutrition” (Note: All of the individual interviews were carried out in the native language)

Researcher: You presented Helmonts’ experiment to your students and asked them the following question: What do you think about the weight of plant and pot of soil? What do you think about your students’ ideas? What do you think are your students’ difficulties?

PST-16: If Murat has such an idea – The willow tree will grow up and an increase in the weight of the tree is equal to the decrease in the weight of the soil, he might have thought that plant fed from the soil. Thus, soil will decrease. I know that such an idea students can have. This is a common misconception. ….Pinar’s response seems correct - The weight of the tree substantially increases, but the weight of soil never changes.. but not completely.…In fact, the weight of the soil will be nearly the same. It means that there is a negligible amount or tiny bit of weight lost by the soil…..The weight lost is due to minerals that plant absorbed through their roots…Plants need a small amount of these minerals to make the enzymes that regulate photosynthesis process….However, students at this age are not likely to put much consideration for such an idea …They may think that these minerals have almost no weight…Ege and Sila also have the similar misconception like Murat - The weight of the plant increases because the plant eat soil…. But there is no soil in the pot at the end, for Sila. Because they probably think that the plant eats the soil. Thus, the soil will be consumed. I believe that their everyday observations or experiences led them to think like that because most children see that any pot of soil reduce at their homes during the time. But theoretically nothing will happen to the soil in the pot if you do not intervene in it. Just you need to change or add the soil due minerals which plants need….. Even some students think that the weight of the soil does not change although the soil should be food for the tree since plants “poop” out waste that adds weight back to the soil…For example, they often observe that plants shed older leaves to the soil and grow new ones while they grow.

Researcher: You presented them results of the Helmonts’ experiment. And this part is about adding water for the growth process of the plant. Then you asked your students the following question: What do you think is the cause of the weight of the plant? You heard similar statements from your students. A difference was that students added, “The weight of the plant can come from the water because he just added it.” What do you think about your students’ ideas?

PST-16: They probably will think that weight of plant will increase because of adding water. If Helmont added only water to the pot of soil, water would cause this. If they have difficulty in understanding the process of photosynthesis, it is acceptable to have such a misconception.

Researcher: You then asked your students the following question: What is your conclusion from Helmont’s experiment? What do you think about your students’ ideas based on their responses?

PST-16: Not only Asli, but a predominant part of the class may think like Van Helmont’s interpretation on his experiment. For the students, scientists are people who do not make mistakes. Even if Helmont misinterpreted water’s role in the photosynthesis process, it is normal for students to think that way. Also, if we are at the beginning of the lesson, it will support this situation….I do not see the classroom level in line with Selin. What Ceren says is correct since it was found that in the experiment of Helmont, water is involved in the photosynthesis process, but it turns out that it is wrong to interpret it. I do think that although Ceren’s thought is right, she does not say it by knowing this fact.

Researcher: What do you think are the sources of alternative conceptions of “plant nutrition”?

PST-16: If these answers came at the end of the course, I could say the teacher or teaching factor. There could be books in the same way. But because they are initial ideas, they are mostly due to previous experiences or other factors. For example, most children observe that their mothers renewed the soil of the flowers every spring. They have also helped their mothers in bringing the soil up to the previous level by adding new soil to the pot. Also, some children have also experienced with feeding the plants with adding the fertilizer to the soil for consumption in some periods. I think that the previous teaching about plant growth used in the lessons and science textbooks may also lead students to hold these learning difficulties…. For example, there are very few textbooks to acknowledge the exceptions in science or models, drawing and explanations in the textbooks may direct students to develop these ideas. For example, “all plants develop fruits through pollination and fertilization” is inaccurate for some fruits such as seedless bananas and pineapples….. I think that these kinds of alternative ideas also result simply from students that have inadequate science knowledge. Most students are confused about what plant groups produce seeds or even what a seed is. Many children may have alternative idea that “Seeds are not alive.”