ARGUMENTATION

SCIENTIFIC ARGUMENTATION

Scientific Argumentation is a key element of Science Practice 6:

The student can work with scientific explanations and theories.

More specifically this Science Practice includes the following:

6.1 The student can justify claims with evidence.

6.2 The student can construct explanations of phenomena based on evidence produced through scientific practices.

6.3 The student can articulate the reasons that scientific explanations and theories are refined or replaced.

6.4 The student can make claims and predictions about natural phenomena based on scientific theories and models.

Scientific Argumentation Process

The process of scientific argumentation involves three components:

1. The first element is the claim, which is the response to a prediction. A claim provides an explanation for why or how something happens in a laboratory investigation.

2. The second component is the evidence, which supports the claim and consists of the analysis of the data collected during the investigation.

3. The third component consists of reasoning, in which students examine and defend one another’s claims. The claims in this step are presented with a rationale of how the evidence supports the claim and why the evidence should count as support for the claim.

Implementing Scientific Argumentation

You can introduce the process of scientific argumentation in a post-lab discussion. You can provide students with directions about how to write a claim and how present their evidence. You will then model how to conduct the discussion.

On the next lab the students can write their claim and evidence summary on their own and you can facilitate the questioning by prompting students to ask and/or respond to their peer’s statements. It is important that students receive explicit instruction in posing meaningful questions that include questions of clarification, questions that probe assumptions, and questions that probe implications and consequences.

Eventually the students will become comfortable leading the scientific argumentation process by questioning, evaluating, critiquing and revising their claims.

http://adi.lsi.fsu.edu/instructional-model

Scientific Argumentation Activity

This is an AP Physics 2 electricity activity that covers the following Learning Objectives:

4.E.4.1: The student is able to make predictions about the properties of resistors and/or capacitors when placed in a simple circuit, based on the geometry of the circuit element and supported by scientific theories and mathematical relationships. [SP 2.2, 6.4]

4.E.4.2: The student is able to design a plan for the collection of data to determine the effect of changing the geometry and/or materials on the resistance or capacitance of a circuit element and relate results to the basic properties of resistors and capacitors. [SP 4.1, 4.2]

4.E.4.3: The student is able to analyze data to determine the effect of changing the geometry and/or materials on the resistance or capacitance of a circuit element and relate results to the basic properties of resistors and capacitors. [SP 5.1]

ACTIVITY:

Students complete an investigation to determine the resistance of a given length of nichrome wire by two independent methods. The post lab discussion asks the students to make a claim by comparing and evaluating the results of the two methods together.

The use of whiteboards for conducting the argumentation process is recommended. On the whiteboard the students write their claim and prepare a summary of their evidence. They can sketch their graphs or attach them to the board using painter’s tape as appropriate. For this investigation students present their data, identify the sources of experimental uncertainty and articulate an evaluation of how experimental uncertainties may have affected the reliability of their measurements.

The students can be seated in a small group or the argumentation can be conducted as a whole-class activity.

EXAMPLE:

Here is an example of one of the discussions with a group of 4 students representing their lab teams

Team 1: Students 1 and 2

Team 2: Students 3 and 4.

Student 1.

Our claim is that our method of using the resistivity model based on the physical dimensions of the wire and the known resistivity of nichrome yielded a better estimate of the resistance of the wire.

Student 3.

What are your sources of uncertainty?

Student 1.

The uncertainty in our experiment is from length measurements: the diameter and the length of the wire. The uncertainty in length measurement is about 1 cm. Our calculations show a percent uncertainty of about 4.5%

Student 4.

What are your assumptions?

Student 2.

We assumed that the wire’s thickness is uniform.

Student 3.

Your reported data shows that the resistivity of the wire is valid for a temperature of 20^o C. Did you guys take into account the temperature of the wire?

Student 1.

No, we didn’t! That is a very good observation we probably should have taken the temperature into account. Can you share your procedure and results?

Student 3.

We took direct measurements of current and potential difference and then we applied Ohm’s law to determine the resistance of the wire.

Student 2.

What are you assuming?

Student4.

We assumed that the resistance of the voltmeter is infinite compared to the resistance of the nichrome wire and we neglected the resistance of the voltmeter leads.

Student 1.

What are your sources of uncertainty?

Student 3.

From our assumption about the voltmeter, we believe that the largest uncertainty is from the ammeter. The uncertainty in the current measurement is about 0.01 A. The percent uncertainty is only 1.4 % as you can see from our calculations so it looks like our estimate of the resistance is closer to the actual value.

Student 1.

It seems like our method is possibly an underestimate due to our having ignored the temperature of the wire. I wonder if your method is an overestimate since you also neglected the resistance in the posts where the nichrome wire connects to the rest of the circuit. The voltmeter must have read a higher value due to this extra resistance.

The discussion continued and as a result of the scientific argumentation process, both teams came to the conclusion that the true value of the resistance of the wire was probably somewhere in between their two estimates. The students were able to revise their claims and make revisions as appropriate.

PARTICIPANTS QUESTIONS:

1. Describe an activity where your students engaged in scientific argumentation.

1. What are the challenges that students face in scientific argumentation?

2. What strategies can be used to help students develop effective questioning techniques?

BACK TO: AP PHYSICS LABORATORY EXPERIENCE

RESOURCES

Llewellyn, Douglas. Teaching high school science through inquiry and argumentation. 2ed. Thousand Oaks, CA Corwin Press, 2013.

Osborne, J., S. Erduran, and S. Simon. 2004. Ideas, evidence and argument in science: Resources pack. London: King’s College. Includes 15 student activities involving scientific argumentation, with lesson plans.

Whiteboarding Strategies. PhysicsEd.BuffaloState.edu.