Capturing student teachers’ pedagogical content knowledge (PCK) using CoRes and digital technology

Figures & data

Figure 1. The ‘PCK Summit Consensus Model’ (Gess-Newsome, 2015, p. 31).

Table

Content: Protein synthesis and heredity Age of students: 15	Big Idea A	Big Idea B	Big Idea C
What do you intend students to learn about this idea?	Two different cell division mechanisms. In the reproductive cell division, the chromosomes of the mother and the father are crossed; i.e. DNA bits are replaced. In this way, the genes are mixed from the parents, which leads to the child being unique.	Heredity. Every person gets genes from mom and dad. These genes can be dominant or recessive. Dominant genes take over the recessive ones, while they need to be two for the individual to get the recessive properties.	That DNA information is translated into RNA. DNA never leaves the nucleus. RNA moves from the cell nucleus to ribosomes. In the ribosomes the information are translated from the RNA and translated into amino acid sequences, thus building up the proteins.
Why it is important for students to know this?	They need to have an understanding of how DNA is transferred during reproduction to provide crossing schemes.	To understand how we inherit some genes. It creates interest in genetic engineering. It's often on national tests, which they will take soon. It is explicitly stated in the biology syllabus.	To understand how the information in the cell nucleus is interpreted and transferred.
What else do you know about this idea (that you do not intend students to know yet)?	Details about the cell division; i.e. all different phases of mitosis and meiosis. Why two daughter cells are formed in mitosis and four in meiosis?	For many genes it is not easy to predict whether they are recessive or dominant. That many genes/proteins interact with each other, affecting the expression and functions.	Concepts such as replication, transcription and translation. All small steps in these processes. That it is protein complexes that complete the functions, and not proteins. That ER also plays a major part in the translation.
What difficulties/limitations are connected with teaching this idea?	If the students want to understand why recombination of chromosomes occurs. If the students want to understand the details of the cell division, then the explanation becomes very complicated.	That both mom and dad have two sets of the same gene, which means that a progeny can inherit in two different ways from their dad and two different ways from their mother. This means that there are four different combinations of the gene set that the offspring can obtain.	This is a very complicated and long chain of mechanisms in the cell. It is easy to go into details and lose a general understanding.
What difficulties/limitations are connected with teaching this idea?	They have already studied cell division and the reproductive organs in previous years.	They are aware that eye colour is a hereditary characteristic. They also know that the environment plays a major role in how characteristics are expressed.	That DNA leaves the cell nucleus. That they do not know what RNA is and how it is related to DNA.
What other factors influence your teaching of this idea?	I think they remember this from previous lessons. I can expect them to remember more than they are doing, which can lead me to go through this area excessively quickly.	That I know too much about gene interaction (I have a PhD in this area) and lose my focus from the main goal of making them understand a crossing schedule. Shortage of time.	That I've been a researcher in this area and that I think it's really interesting. I can find it difficult to delimit and clarify complex mechanisms.
What teaching procedures will you use and what are the particular reasons for using these to engage with this idea?	Explanation with the help of pictures and discussions.	Exercises with whole class and then individually.	Drawing sketches on the board and ask students to summarise.
What specific ways do you have of ascertaining students’ understanding or confusion?	First, I ask my students what they remember from last year. Then we discuss it. Lastly, they may show the thumbs up, horizontally or downwards, depending on whether they understand.	I move around the classroom and help them to start. I look at their exercises. We will also do more exercises the next lesson.	I ask individual students to summarise what I have told them.

Gess-Newsome, J. (2015). A model of teacher professional knowledge and skill including PCK: Results of the thinking from the PCK Summit. In A. Berry, P. Friedrichsen, & J. Loughran (Eds.), Reexamining pedagogical content knowledge in science education (pp. 28–42). London: Routledge.

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