Practice of Science

Scientists frequently repeat the experiments of others scientists. Why is this important in science?

• Scientists often ask each other for help in performing experiments.

• Replication of experiments helps to confirm and verify results.

• Scientists frequently perform other scientists’ experiments in order to practice their technique.

• Repeating experiments is an effective way to make sure a laboratory is in optimal condition.

Cara read an article on why repetition and replication are so important, but she did not understand the difference between them. Which of the following best explains the two terms?

• Repetition is when a scientist repeats an experiment; replication is when a scientist conducts an experiment on genetic material.

• Repetition is when a scientist does the same experiment a number of times; replication is when other scientists reproduce a scientist’s experiment.

• Repetition is when a scientist publishes in more than one scientific periodical; replication is when another scientist reproduces another scientist’s results.

• Repetition is when a scientist commits an error in an experiment the first time and must repeat it; replication is when a scientist repeats an experiment to make sure it is valid.

Kaylee reads an article that states that the frequency of chirping by crickets is related to the temperature of

their environment. She wants to conduct an experiment to see if this is true. Kaylee states this hypothesis:

Crickets chirp more frequently when the temperature of their environment increases. What is the test

variable (independent variable) and outcome variable (dependent variable) in Kaylee’s experiment?

• test variable (independent variable): number of crickets; outcome variable (dependent variable): frequency of chirping

• test variable (independent variable): temperature of environment; outcome variable (dependent variable): frequency of chirping

• test variable (independent variable): number of crickets; outcome variable (dependent variable): temperature of environment

• test variable (independent variable): frequency of chirping; outcome variable (dependent variable): temperature of environment

The independent variable is the ONE thing you _____.

• change on purpose
• control or keep constant
• measure

Tags

NGSS.MS-PS2-2

The variable that is being measured or observed is called the _______________.

• independent variable

• dependent variable

• control variable

Tags

NGSS.MS-PS2-2

What are constant/controlled variables in an experiment?

• Variables that remain constant across all groups.

• Variable that the scientist changes in the experiment.

• It's the variable that is being measured in an experiment

Tags

NGSS.MS-PS2-2

Edgar conducted an experiment to determine if distance effects apparent magnitude (brightness). After gathering the materials, he measured four different distances from the wall. While holding and aiming the light source at a point on the wall, he stood at each of the four distances. He observed and recorded the apparent brightness at each distance.

Which of the following correctly describes the independent variable in Edgar's experiment?

• Distance of light source from the wall

• Amount of brightness observed at varying distances

• Object used as the source of light

Edgar conducted an experiment to determine if distance effects apparent magnitude (brightness). After gathering the materials, he measured four different distances from the wall. While holding and aiming the light source at a point on the wall, he stood at each of the four distances. He observed and recorded the apparent brightness at each distance.

Which of the following is the best list of variables that need to be controlled (controlled variables/constant variables) in Edgar's experiment?

• qualitative data describing the brightness that was observed

• 25 cm, 50 cm, 75 cm, 100 cm

• light source, room used for experiment, identified point on the wall and amount of light coming in from other sources

• light source, metric ruler, pencil, and distance of light source

What is the outcome (dependent) variable?

• plant height

• time in days

• sunflower

• daisy

Tags

NGSS.MS-LS1-5

Based on the data shown in the graph, which of the statements below mostly closely fits the data.

• Students didn't perform as well on test #4 as they did on test #7

• Students performed better on test #4 than they did on test #9

• Students performed better on test #1 than they did on test #7

• Students didn't perform as well on test #1 as they did on test #8