The Scientific Method

Which steps are important when designing and conducting a scientific experiment?

• Hide the results from fellow scientists.

• Identify the independent variable.

• Eliminate all dependent variables.

• Address any confounding variables.

• Form a non-falsifiable hypothesis.

Tags

NGSS.HS-LS1-3

What is a scientific theory?

• a reasonable guess based on instinct

• an imaginative idea explaining natural phenomena

• a broad, evidence-based explanation for a phenomenon

• a tentative statement with little or no predictive power

Answer explanation

A theory EXPLAINS the HOW and WHY of something.

Hakeem is testing the effects of sunlight on samples of soil. Which of these actions would introduce confounding variables into Hakeem’s experiment?

• He tests a theory that’s already been established.

• He tests multiple hypotheses at a time.

• He uses identical specimens when completing multiple trials.

• He adjusts the independent variable and records the effects.

• He uses different types of soil in each of his samples.

Why is this statement not a hypothesis?

Sunflowers require soil and plenty of sunlight and water to grow and thrive.

• It is a well-known fact.

• It is a proven theory.

• It is not falsifiable.

• It is difficult to test.

Answer explanation

a hypothesis is a proposed explanation for an occurrence based on available data, observations, or evidence

Tags

NGSS.HS-LS1-3

When Raymond observes certain natural phenomena, he often forms ideas about their causes and effects. Suppose that Raymond surmises that leaves change color in autumn due to scarcity of sunlight. In order to test whether his idea is accurate, he must first construct a falsifiable ____________ that defines a clear relationship between two variables.

• theory

• law

• hypothesis

After constructing a falsifiable hypothesis, Raymond’s next step is to ____________ that would isolate and test the relationship between the two variables.

• design an experiment

• complete mathematical calculations

• propose an explanation

Tags

NGSS.HS-PS3-3

The task of designing an experiment can be pretty daunting because Raymond will need to identify and eliminate any __________ variables that could confuse test results.

• dependent

• confounding

• independent

Answer explanation

Confounding Variable: an additional variable, aside from the independent and dependent variables, that may influence the outcome of an experiment.

Madison lives near the ocean. She’s formed a hypothesis that increased concentrations of salt in the air speeds the corrosion of certain metals. If Madison plans to test this hypothesis, she will have to deal with which DEPENDENT VARIABLE in her experiment?

• air humidity

• air temperature

• amount of metal corrosion

Answer explanation

dependent variable:

a tested variable in a scientific investigation;

a dependent variable is affected by changes made to the independent variable.

It is the change you are observing during an experiment.

Tags

NGSS.HS-PS1-5

Madison lives near the ocean. She’s formed a hypothesis that increased concentrations of salt in the air speeds the corrosion of certain metals. If Madison plans to test this hypothesis, she will have to deal with which INDEPENDENT VARIABLE in her experiment?

• airborne salt concentrations

• volume of ocean water

• ocean water temperature

Answer explanation

independent variable:

a variable controlled by the scientist during a scientific investigation.

Madison lives near the ocean. She’s formed a hypothesis that increased concentrations of salt in the air speeds the corrosion of certain metals. If Madison plans to test this hypothesis, she will have to deal with which ONE POSSIBLE CONFOUNDING VARIABLE in her experiment:

• color of nearby ocean waters

• airborne salt concentrations

• air temperature