Pedagogical Content Knowledge Development in Experienced Biology Teachers in Their First Attempts at Teaching a New Topic

Abstract

It is not uncommon for teachers to be required to teach new content due to curriculum changes or shifts in teaching assignments. The former is particularly the case for science teachers because of the advancement in science. However, there is little research on how experienced teachers may develop the requisite knowledge for teaching new topics that they have never taught before. Hence, we explored how six experienced biology teachers prepared for and enacted their first-time teaching of a new topic, polymerase chain reaction, in the context of a curriculum change. Pedagogical content knowledge (PCK) was used as the lens to examine the teachers’ development of topic-specific knowledge. In this chapter, we aim (1) to illustrate how new PCK development can be facilitated by a teacher’s disposition to enact two pedagogical moves, namely, conducting subject matter analysis and assessing students formatively, and (2) to characterise the instances in which the teachers invented new instructional strategies/representations during the interactive phase of the lesson (i.e. on-site PCK development). The mechanism of on-site PCK development as a three-step process is also proposed. Implications on teacher professional development arising from the findings are discussed.

Appendix

Teacher	Brandon
Lesson	Lesson 2
Theme	(2) Primers and annealing of primers
Vignette	B. The function of primers II
Analysis
What did the teacher do?				Data sources
In the second lesson, the teacher used an analogy he invented on the spot of the lesson to explain the functions of primers (i.e. to provide a starting site for the synthesis of DNA), when revisiting the important concepts taught in the first lesson.				Observation
				Field notes
				Lesson transcript
				Pre-lesson interview
				Post-lesson interview
				Stimulated recall interview
Description of student-teacher interaction
B:	Primer acts like an initiation point. When its position is recognised by the DNA polymerase, it starts (the DNA synthesis). In the athletic meet, do you know where you should start running for the 100 m race in the field track?
Ss:	Inaudible
B:	Where should you start running for the 200 m race?
Ss:	Inaudible
B:	How about running for the 400 m race? Do you also know that? For 1500 m race, where should you start running? It is easier to locate the (starting) position for 100 m race and 200 m race. How about that for 1500 m race?
S1:	At the position for 200 m race.
B:	Is it really that 1500 m race starts at the position line for 200 m race?
Ss:	Inaudible
B:	Where should it be? It should be near the position for 300 m race. How do you know that you’re standing at (the starting position for) 300 m race. Actually, what do you rely on (to know the starting position)?
S2:	Someone would tell you!
B:	Besides that, there is a track judge. Primer is a chemical substance. It is actually some short DNA fragment. It would anneal to the (DNA) template. Then, the DNA polymerase and the following nucleotides for making the (new) DNA would recognise that point as the starting point and “line up” there.
	….
B:	After the DNA has separated into two strands, what would happen? The process is called primer annealing. The primers would anneal to a specific location (of the DNA to be amplified). It is like the track judge. Depending on whether you go for 100 m race, 200 m race or 1500 m race, the track judge would lead you to the specific location (in the field track)(Lesson Transcript #2).
PCK components integrated in the episode				Data sources
Knowledge of Students	Knowledge of instructional strategies	Knowledge of assessment	Knowledge of curriculum	Observation
				Field notes
				Lesson transcript
✓	✓			Pre-lesson interview
				Post-lesson interview
				Stimulated recall interview

Evidence of the presence of PCK components identified in the episode	Data sources
The concepts about primer are a bit more difficult. They don’t know what a primer is. I think the ideas about primer are the more problematic part (Post-lesson interview #1) (knowledge of students)
I thought I was not teaching the ideas about primers well yesterday. The primers provide a starting point (for the DNA polymerase to start DNA synthesis). What is the meaning of a starting point? Different primers provide different starting points (along the DNA to be amplified). I, then, thought about how to express the ideas at that moment. … The competition (analogy) was just off my head. … At that moment, I think they were confused. Primer is a DNA fragment that anneals to the DNA. When annealed, the DNA polymerase and nucleotides would start to work (on DNA synthesis). … The analogy was used to make the ideas concrete. … I really didn’t think about this (confusion) yesterday as I had taught them this (idea) yesterday (in the lesson) (Post-lesson interview #2) (knowledge of instructional strategies, knowledge of students)	Post-lesson interviewsStimulated recall interview
I felt that they were not able to follow (the ideas I was teaching) from their facial expression. … Then, I started to think about how to make the ideas easier. Many students studied PE (physical education). … When they (students) have field events, they know where the starting position for the 100 m, 200 m and 400 m sprints is (in the field, respectively). So, I used this analogy to talk about the concepts (Stimulated recall interview) (knowledge of instructional strategies)
I just observed their faces. … At that interaction, I think they don’t seem to understand (the idea about the primers). The concept is about recognising the location (by the DNA polymerase) and that the DNA strand extends from that position. … I thought about their daily life experiences. At that moment, I thought that running may be related to this idea. I think that running is something that they have experienced (Stimulated recall interview) (knowledge of instructional strategies, knowledge of students)