Making unseen processes visible:Looking at DNA replication in a test tube

Hagit Yarden and Anat yardenDepartment of Science TeachingWeizmann Institute of Science

Rehovot, Israel

Yarden, H. & Yarden, A. (2009). Learning using dynamic and static visualizations: Students’ comprehension, prior knowledge and conceptual status of a biotechnological method. Research in Science Education, In press

Outline

• Problem• Context• Objective• Approach• Results• Conclusions

The problem

• Molecular biology methods are unfamiliar to most students: remote from everyday experiences, no hands-on in school lab (i.e., Olsher

et al., 1999) • Students have difficulties in acquiring a

coherent cognitive model of modern genetics:- Comprehending abstract concepts: DNA, RNA,

gene, chromosome, protein; and process: DNA replication, transcription, translation (i.e., Malacinski & Zell, 1996)

Objective

To investigate the unique contribution of animations in facilitating students’

understanding of molecular processes in the context of learning biotechnological

methods

Context• 12th graders

• Biology majors

• Study ‘Gene Tamers—Studying Biotechnologythrough Research’ (Falk et al. 2003), based on AdaptedPrimary Literature (APL)

• In the Methods section of APL: Polymerase Chain Reaction (PCR) - synthesize multiple copies of a desired DNA fragment in a test tube (Mullis, 1983)

http://stwww.weizmann.ac.il/g%2Dbio/biotech/mavo-methods.html

Methodology• Population: 12th graders (17-18 yrs old, n=173),

biology majors, 9 classes, 2006-2007 academic year

• Research approach: both quantitative and qualitative

• Data sources: students' prior content knowledge questionnaire, students’ post questionnaires, audiotapes of verbal interactions of pairs of students while using the animation or the cards

Methodology (cont.)• Analysis of audiotapes: 4 transcripts of

animation group and 4 of the cards group• Qualitative analysis: based on the conceptual

change framework (Hewson & Lemberger, 2000; Tsui &

Treagust, 2007) • Quantitative analysis: collect all status

elements, group them under the relevant conceptual status

Methodology (cont.)

Intelligibility

Plausibility

Fruitfulness

i.e., image, language

i.e., real mechanism, metaphysics

i.e., promise

Status elements for analyzing conceptual status:

(Hewson & Lemberger, 2000; Tsui & Treagust, 2007)

Research questions• Is there a difference in the comprehension of PCR between students who learned using animation and those who learned using still images?

• What are the relationships between students' prior content knowledge and their comprehension of the PCR method, using animation or still images?

• What is the difference in conceptual status of the PCR method between students who learned using animation and those who learned using still images?

Results:A significant advantage for the animation group vs.

the still images group in the post-questionnaires

***p<0.001

Research questions• Is there a difference in the comprehension of PCR between students who learned using animation and those who learned using still images?

• What are the relationships between students' prior content knowledge and their comprehension of the PCR method, using animation or still images?

• What is the difference in conceptual status of the PCR method between students who learned using animation and those who learned using still images?

Results:Still images group: Relatively high correlation between prior knowledge and understandingAnimation group: Relatively low correlation between prior knowledge and understanding

Research questions• Is there a difference in the comprehension of PCR between students who learned using animation and those who learned using still images?

• What are the relationships between students' prior content knowledge and their comprehension of the PCR method, using animation or still images?

• What is the difference in conceptual status of the PCR method between students who learned using animation and those who learned using still images?

Results:• The function of DNA Polymerase:Animation group:2: So [DNA] polymerase is causing the small ones [the nucleotides] (+image), right? (+real mechanism)1: Yes, and this is why they put a lot of them [nucleotides], so instead of only two strands there will be a lot of them (+real mechanism)

Cards group:1: What does it mean? They [the primers] are already attached, so what does it [the DNA polymerase] do? (-metaphysics)2: Maybe it [the DNA polymerase] is connecting between them [the primers], I don't know… (-real mechanism)

Results:• The function of the primers:

Animation group:The primers are those we saw in the beginning [of the animation], which are attached in 45oC, those big small ones (+image), I think they are involved in the initial stages of the process (+language).

Cards group:1: They serve as enzymes, right?2: I think they are. (-metaphysics)

Results:• The specific temperatures at which different stages in the PCR method occur:Animation group:2: O.K, but in the question they are asking why these [the primers] are attached and not these [the DNA strands]?1: Because they are smaller (+real mechanism). The primers are starting (+language), and then the DNA polymerase is helping to complete them [the DNA strands] (+real mechanism).Cards group:1: "We heat the mixture to 65oC. At this temperature, the DNA polymerase creates… At the end of this cycle, we end up with two copies of the original double-stranded DNA molecule" [reading from the text].2: Well, no, I did not understand it (-real mechanism). Move, move to the next card…

Results:• Significant advantage

for the animation group vs. the still images group in the conceptual status category: Plausibility (real mechanism and metaphysics, p<0.001)

Conclusions

• The use of the PCR animation provides an advantage to learning the method vs. still images

• Low prior knowledge does not harm students’ ability to learn the PCR method if they use animation

• Students from both groups reached the stage of intelligibility, while the next level – plausibility – appeared only among students who learned using the animation

Acknowledgments

• Hagit Yarden

• Hedda Falk• Rachel Cohen• Michal Stolarsky Ben-Nun• Eilat Hasson• Yardena David• Ronit Rozenszayn• Carmit Shpalter• Yossy Machluf