module 3

Question 1

a. Experimental variable

Answer 1

An aspect of an experiment that changes during the course of the experiment

Question 2

b. Control (of an experiment)

Answer 2

The variable or the part of the experiment to which all others will be compared

Question 3

c. Blind experiments

Answer 3

Experiments in which the participants do not know whether or not they are a part of the control group.

Question 4

d. Double-blind experiments

Answer 4

Experiments in which neither the participants nor the people analyzing the results know who is in the control group.

Question 5

2. When is an experimental variable good and when should it be reduced or eliminated

Answer 5

An experimental variable is good when you are using it to learn something from the experiment. An experimental variable should be reduced or eliminated when it affects the results of the experiment but you do not learn anything from it.

Question 6

3. What was the control for that experiment

Answer 6

The shirt that is being washed with no laundry detergent at all

Question 7

4. What is the experimental variable that will be used to learn something from the experiment?

Answer 7

The type of detergent used.

Question 8

5. What are the experimental variables that need to be reduced or eliminated?

Answer 8

The washers are different, water can be at different temperatures, the shirts are different, the amount of grass stain will be different in each shirt.

Question 9

6. What could be done to reduce or eliminate the unwanted experimental variable

Answer 9

The experimental variable of the washers can be reduced by making sure all washer are the same brand and model.

Question 10

7. Are the data collected objective or subjective?

Answer 10

The data being collected are subjective

Question 11

8. Why can a carefully placed needle float on water, even though a needle is denser than water?
   Surface tension

Answer 11

Surface tension

Question 12

9. What does soap do to the surface tension of water?

Answer 12

reduces