PURPOSE: In this activity, you will practice graphing the results of an experiment. You will also learn what constitutes a valid experimental procedure.
PROBLEM: How many drops of water will fit onto the “Lincoln” side of a penny?
PREDICTION (Hypothesis): I predict that ____ drops of water will fit on the head side of a penny.
A constant is things in an experiment that are kept the same in all trials.
1. In this experiment, there were a limited number of constants. Name two of them.
An independent variable is changed on purpose by the experimenter.
2. What was the independent variable in this experiment?
3. Where is the independent variable located on a graph?
A dependent variable is a variable that responds to the independent variable.
4. What was the dependent variable in this experiment?
5. Where is the dependent variable located on a graph?
A control variable is a test group that does not receive the independent variable.
6. Based on this experiment, is there a control group present? If so, what is it?
Validity is a measure of how correct the results of an experiment are. Think about what makes an experiment valid.
7. Using your bar graph, determine if the average number of drops for each group is about the same. List four reasons why the actual number of drops for each group was similar or dissimilar.
8. Are the results of this experiment “valid”? Why or why not?
9. What would happen if you used the other side of the penny? When comparing data with the rest of the class, why would it be important that we all use the same “Lincoln” side of the penny?
7. The average number of drops for each group is similar because:
a) All trials were conducted with the same type of penny.
b) All trials were conducted by using the same procedure.
c) The same type of water dropper was used for all trials.
d) The same amount of time was given for the drops to be added.
8. The results of this experiment are "valid" because all the necessary controls were in place. The experiment was conducted in a consistent manner, with the same conditions for each trial.
9. If the other side of the penny was used, it may affect the results as the texture and surface properties of the two sides could be different. It is important that we all use the same "Lincoln" side of the penny to ensure consistency and comparability of the data across different experiments.
1. In this experiment, two of the constants are the type of penny used and the method of counting the drops of water.
2. The independent variable in this experiment is the number of drops of water.
3. The independent variable is usually plotted on the x-axis of a graph.
4. The dependent variable in this experiment is the number of drops of water that fit on the "Lincoln" side of the penny.
5. The dependent variable is usually plotted on the y-axis of a graph.
6. In this experiment, there is no control group since all groups are being tested with the same independent variable (number of drops of water).
7. To determine if the average number of drops for each group was about the same, you would examine the bar graph. Four reasons why the number of drops for each group may be similar or dissimilar could include variations in the surface tension of the water, differences in how drops were counted or measured, variations in the angle or position of the penny, and individual differences in the shape or condition of each penny.
8. The validity of the experiment depends on various factors, such as the consistency of the experimental procedure, the accuracy of measurements, and the reliability of the data collected. Without additional information, it is not possible to determine if the results of this specific experiment are "valid."
9. If you used the other side of the penny, the data would be different. It is important for all participants to use the same "Lincoln" side of the penny to ensure consistency and comparability of data when comparing results with the rest of the class.