Practice Problems: Scientific Argumentation and Graphing

1.(easy) A question is raised in a science class about why there are seasons for much of the Earth. Identify the claim, evidence and justification in the poorly made argument shown below that was created to answer the question. Critique the argument using the concepts discussed in the presentation.
"Everyone understands the concept that the closer you are to a source of heat, the warmer it is. Seasons occur because the Sun is closest to the Earth during the summertime in North America. We know this because the average temperature in Pittsburgh is the highest in June, July, and August."
Claim: Seasons occur because the Sun is closest to the Earth during the summertime in North America
Evidence:  We know this because the average temperature in Pittsburgh is the highest in June, July, and August.
Justification: Everyone understands the concept that the closer you are to a source of heat, the warmer it is.

This is a invalid argument because the surface temperature of the any part of the Earth is primarily due to the amount of sunlight it receives per day. The rotation of the Earth on its imaginary axis, and the fact that the axis is tilted relative to its orbital plane, allows for the Earth's seasons because the number of hours of daylight varies as a result. The difference in distance from the Earth to the Sun at various times of the year does not significantly contribute to this phenomenon.

2. (moderate) A group of students measured the position of an object moving away from an arbitrary zero point along a straight line at various times. Graph the data showing position vs. time. Determine the equation of the line of best fit for the data. Use the equation to find the position when the time is 6.6 s.

When t = 6.6 s, the position of the object can be calculated using the equation for the line of best fit:

y = position = 2.0064(6.6) - 0.0136 = 13.2 m

3. (moderate) The following scenarios were found in a research study titled Using a Pseudoscience Activity to Teach Critical Thinking (Adam and Manson, 2014 - see citation below). For each scenario identify any claim, evidence, or justification (rationale) statements. Then state why each is flawed.
In each scenario the claim is highlighted in yellow, evidence is highlighted in green, and the justification is highlighted in blue. Not all scenarios contain all three components.

Scenario 1: Bill’s mom told him that taking vitamin C will cure a cold. The very next time Bill caught a cold he drank three glasses of orange juice every day for 5 days. Orange juice contains vitamin C. At the end of the fifth day, Bill’s cold was gone. Bill concluded that vitamin C cures colds.
The justification has no scientific backing. Unless Bill's mom is a scientific researcher, her opinion does not justify the argument.

Scenario 2: A famous Nobel Prize–winning scientist announces that magnets can relieve back pain when rubbed on a person’s back. He found 10 people with back pain and gave each of them magnet therapy. After the therapy, most of the people told him that their back pain was reduced. He concluded that magnets relieve back pain. 
The justification has no scientific backing. The fame of a scientist does not justify the relationship of the evidence to the claim.

Scenario 3: You see a new ad for a pill that claims to enhance the body’s natural ability to concentrate while driving. The ad features a famous race car driver who races a track he has never raced on both before and after taking the pill. He does much better the second time after taking the pill. The ad concludes that taking this pill will enhance your driving abilities.
There is no rationale in this argument and the evidence is extremely weak.

Scenario 4: A teacher feels better when wearing bright colors. She hypothesizes that wearing brightly colored clothing can also improve the mood of people around her. She tests this using her students. She wears dull clothing to her morning class of 45 students and brightly colored clothing to her afternoon class of 45 students. She reports that her afternoon class seemed more alert and smiled more. She concludes that wearing bright colors improves other peoples’ moods.
The evidence is extremely weak and hypothesis does not have strong support. The rationale is only an opinion.

4. (moderate) All scientific arguments are not equal. Some are better than others. Since arguments are composed of three distinct components, it's often helpful to analyze the strength of each component in an argument. The following information helps one to determine the strength of the various components:
Claims: Strong claims answer the question being asked. Strong claims indicate cause and effect, often using the word "because" and are written in complete sentences.
Evidence: Evidence is strong when it is based on a pattern in the data. Strong evidence is reliable in that it comes from multiple trials or observations. Strong evidence doesn't violate known physical laws. An evidence statement is strengthened when it is combined with other evidence that also supports the claim.
Justification: Strong justification uses science terms appropriately and uses accepted scientific concepts to explain the connection between the claim and the evidence. 
Imagine that you were tasked with answering the following question:

"When a woman is on a moving walkway (the kind you see at airports) and tosses a ball vertically into the air, why doesn't the ball land behind her?"

a. Rank the following claims from weakest to strongest:
Claim #1: The ball will not land behind her because it was already moving forward (relative to the ground, not the moving sidewalk) prior to the vertical toss. Strongest
Claim #2: The ball will not land behind her because I've never seen that happen. 
Claim #3: The ball will not land behind her because gravity pulls it downward. Weakest

b. Rank the following evidence statements from weakest to strongest:
Evidence Statement #1: I observed this phenomenon many times at the airport. The ball never lands behind the person tossing it.
Evidence Statement #2: When an object is dropped from an airplane, it doesn't fall straight downward. Instead it continues moving forward while it falls. Strongest
Evidence Statement #3: I watched the woman conduct the experiment. Weakest

c. Rank the following justifications from weakest to strongest:
Justification #1: The conservation of energy is a bedrock scientific principle. If the ball landed behind the woman, this principle would be violated. Weakest
Justification #2: Gravitational force is described by a physical law which that all masses attract all other masses. The ball must fall down toward the Earth.
Justification #3: The physical concept of inertia is a well established scientific fact. It states that an object continues in its state of motion unless acted on by a net external force. Although the gravitational force acted vertically, no significant force acted horizontally. (We are assuming negligible air resistance.) Strongest

5. (moderate) Students collected data on a gas as shown below. What is the nature of the relationship between the pressure and the volume of the gas according to this data. Use a graph to support your answer. Is there a way that you can "linearize" the graph? In other words, what can be done with the data so that a new plot will show a linear relationship between one of the measured values and a modification of the other? Create this new graph to show the linearization.

The graph shows an inverse relationship between volume and pressure. The relationship can be linearized by plotting V vs. 1/P as shown below.

Here is a chart that will help you to categorize various mathematical models for graphing and how to linearize them when needed.

Adam, A., & Manson, T. M. (2014). Using a pseudoscience activity to teach critical thinking.Teaching of Psychology, 41(2), 130-134. doi:10.1177/0098628314530343