Yes, there is a control group present in this experiment. The control group is the test group that does not receive the independent variable, in this case, the "Lincoln" side of the penny.
Validity in an experiment refers to how accurately the results reflect the true relationship between the variables being tested. An experiment is considered valid when it has a well-designed procedure, controls for all confounding factors, and produces reliable and consistent results.
To determine if the average number of drops for each group is about the same, one would need to create a bar graph comparing the average number of drops on the "Lincoln" side of the penny for each group.
Four reasons that could explain why the actual number of drops for each group is similar or dissimilar could be:
1. Variations in the surface tension of the water droplets.
2. Variations in the size or shape of the drops.
3. Differences in the angle at which the drops were applied to the penny.
4. Differences in the cleanliness or smoothness of the surface of the penny.
The results of this experiment can be considered valid if the procedure was followed correctly and all relevant variables were controlled for. If there were any inconsistencies or errors in the experimental procedure, the results may be less valid.
If the other side of the penny were used in the experiment, it may have a different surface texture or characteristics compared to the "Lincoln" side. Therefore, the number of drops that can fit on the other side of the penny may be different. To compare data with the rest of the class, it is important to use the same side of the penny (in this case, the "Lincoln" side) to ensure consistency and accuracy in the results.
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? A control variable is a test group that does not receive the independent variable.
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.
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.
Are the results of this experiment “valid”? Why or why not?
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?
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