Experiment Prep

Which of the following describes the independent variable?

• The factor you add in an experiment; it is not the "effect," but you are seeing if the independent variable leads to the "effect."

• The "effect" as a result of something else. The "response" that you measure at the end of the experiment/trial.

Which describes the dependent variable? Check all that apply.

• The outcome of an experiment.

• The effect the independent variable is believed to cause.

• The result of the experiment.

• The factor you measure BECAUSE of the independent variable.

What is the purpose of having a "control group" in an experiment?

• To make politicians happy.

• To establish a baseline to compare to.

• So that the results make sense.

• Without the control group, everyone would be in danger.

What is the difference between those in the control group and those in the experimental group?

• The experimental group is the baseline.

• The independent variable is not a factor in the control group, so we can establish a baseline comparison.

• The control group is not measured the same way as the experimental group.

• Both are exactly the same.

I am investigating how lime in the soil affects plant growth. I am measuring the plant growth by counting how many leaves they have. What is the independent variable?

• Lime

• Soil

• Plants

• Number of leaves

I am investigating how lime in the soil affects plant growth. I am measuring the plant growth by counting how many leaves they have. What is the dependent variable?

• Lime

• Soil

• Plants

• Number of leaves

I am investigating how lime in the soil affects plant growth. I am measuring the plant growth by counting how many leaves they have. Select the best option for a control group.

• Grow different plants than the ones in your experimental group. Give them extra lime.

• Grow the same kinds of plants in the same conditions as the ones in your experimental group, but provide no lime.

• Grow no plants in the soil and see how much lime appears.

• Grow plants that cannot grow leaves so you can be sure the lime works.

I am investigating how a new kind of mouth wash might influence mouth health. I am measuring mouth health by swabbing patients' mouths and counting the bacteria density in their mouths. What is my dependent variable?

• Mouthwash

• The volume of mouthwash they use each day.

• The type of bacteria.

• The density of bacteria in their mouths.

I am investigating how a new kind of mouth wash might influence mouth health. I am measuring mouth health by swabbing patients' mouths and counting the bacteria density in their mouths. What would be good constants to establish? Check all that apply.

• The frequency with which they brush their teeth.

• Any nutrition habits/supplements.

• The length of their hair.

• The type of tooth paste they use.

I am investigating how a new kind of mouth wash might influence mouth health. I am measuring mouth health by swabbing patients' mouths and counting the bacteria density in their mouths. Which of the following is the best hypothesis? (Remember the three things a good hypothesis needs).

• If people use this mouth wash, their mouths will get healthier.

• If people use this mouth wash, their mouths will contain less bacteria because this mouth wash contains a chemical known to prevent bacterial growth.

• If people use this mouth wash, then they might have better mouths because this stuff is powerful.

• There will be less bacteria.