SSA Review (Scientific Method)

A 9-kilometer-wide meteorite hit Earth 65 million years ago. Scientists have found a high concentration of iridium in the sedimentary layer from this time period. Iridium is very rare in Earth’s crust, but it is abundant in meteorites. Scientists believe this impact ended the Cretaceous Period and caused the dinosaur extinction. Which of these statements correctly describes whether this is a theory or a law and why?

• It is a law because it includes a numerical analysis.

• It is a law because it explains all causes of animal extinction.

• It is a theory because it explains the cause of the dinosaur extinction.

• It is a theory because it shows regular patterns from an analysis of the data.

Tags

NGSS.MS-LS4-1

Why is it useful to have debate within the scientific community when a new theory is introduced?

• It is a way to slow down change that would result in disruptions in the way science is taught.

• It is human nature that other scientists want to express their opinions before they are open to accepting new theories.

• Debate on new theories limits the cost of change because new science often changes technology and disrupts the economy.

• Debate allows other scientists to challenge or defend the logic of new theories in ways that the first scientists might not have considered.

In the nineteenth century, the flow of electricity was commonly used but poorly understood. Steinmetz developed a simple mathematical model that allowed him to make predictions. His model has been modified but is still used today. Which conclusion about scientific progress is best supported by this example?

• Scientific ideas are interpreted best by those who discover them.

• Scientific ideas must be well-developed before they are practical.

• Scientific ideas can be built upon over time by a variety of people.

• Scientific ideas from one generation do not apply to new generations.

A scientist uses a computer model to investigate how heat flow in Earth's mantle results in the motion of tectonic plates. Which of these statements describes a benefit of using a computer model to simulate interactions in Earth's layers?

• The model allows scientists to more reliably prevent the motion of tectonic plates.

• The model allows scientists to more directly observe the motion of tectonic plates.

• The model allows scientists to more carefully change the motion of tectonic plates.

• The model allows scientists to more accurately predict the motion of tectonic plates.

Tags

NGSS.HS-ESS2-3

NGSS.HS-ETS1-4

Astronomers study objects as large as galaxies. Chemists study objects that can be as small as an atom. Which of the following is common to scientists working in different fields of science?

• both fields use the same technology

• both fields require the same basic knowledge

• both fields are based on the same experiments

• both fields use the same basic scientific methods

Pollution has many causes and can affect the air and water quality in a variety of ways. Nitrates are a common pollutant found in agricultural runoff. Four groups of students designed experiments to determine the effect of nitrates on algae growth. Which group of students designed an experiment whose variables would lead to the most valid results?

• Group 1 varied both the temperature and the amount of nitrates.

• Group 2 kept both the temperature and the amount of nitrates constant.

• Group 3 kept the temperature constant and varied the amount of nitrates

• Group 4 varied the temperature and kept the amount of nitrates constant.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

NGSS.MS-LS2-4

A scientist is researching the effects of a new drug on the symptoms of a disease. She plans to conduct a controlled scientific experiment testing the drug’s effects. Why is it important to REPLICATE scientific experiments?

• to compare the experimental results with current drugs used to treat the disease

• to allow other scientists to conduct the same experiment to confirm experimental results

• to provide the scientist with results from a group with which to compare the experimental results

• to manipulate only one variable at a time to provide the scientist with more reliable experimental results

Misha thinks that hot water can dissolve more sugar than cold water. To test this, Misha fills three beakers with water. One beaker is kept at room temperature, the second beaker is heated on a burner, and the third beaker is refrigerated for one hour. Misha then adds the same amount of sugar to each beaker, stirs 10 times, filters out the remaining solid sugar, and records the mass of sugar left undissolved in each beaker. How can Misha improve the validity of the results?

• conduct more trials of the experiment

• add a control group to the experiment

• create a hypothesis for the experiment

• add another variable to the experiment

Tags

NGSS.MS-PS3-4

Shawn will conduct a study by rolling a toy car down a ramp. He plans to set the height of the ramp at 30 centimeters (cm) and record the time it takes to reach the end of the ramp. He will add a 10g block to the toy car and record the time. He will add another 10g block to the toy car and record the time. Which statement correctly identifies the independent and dependent variables?

• I: Mass

  D: Time

• I: Height

  D: Time

• I: Height

  D: Mass

• I: Mass

  D: Height

Tags

NGSS.MS-PS2-2

NGSS.MS-PS3-1

Katia plans an experiment that measures the temperature of different colors of paper placed in sunlight. Her hypothesis is that if black, blue, yellow, red, and white sheets of paper are exposed to sunlight, then the black sheet of paper will increase the most in temperature. Katia will place a sheet of each color of paper in the same location for the same amount of time. What are the independent and dependent variables?

• I: Color of paper

  D: Temperature

• I: Temperature

  D: Color of paper

• I: Amount of sunlight

  D: Temperature

• I: Amount of time

  D: Temperature

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5