Lab Activity No. 1

The Scientific Method

Survey of Biology Lab

A. Objectives: Upon completion of this lab activity, you should be able to:

1. Explain the purpose and the general process of the scientific method.

2. Distinguish between a testable question and a hypothesis.

3. Develop a testable question that is appropriate for a specific experiment.

4. Design an experiment and critically evaluate this design.

5. Collect and present data in tabular and graphical formats.

6. Critically evaluate and interpret the data from your experiment.

7. Based on evaluation of the data, state an appropriate conclusion.

8. Explain the implications of the experiment.

9. Apply your experiences in this activity to any other example.

B. Introduction: While reading a magazine, you observe an advertisement for a particular brand of paper towels. In this ad, the statement is made that this brand of towels is superior to other brands with respect to two characteristics: total water absorbency and strength when wet. You are puzzled, because you remember another advertisement for a different brand that made the same claim. Being the “scientific type”, you decide to design and conduct an experiment to determine which of the two brands is superior for one of the two characteristics. Note: Each group will be assigned one characteristic to evaluate.

C. Designing and Conducting a Scientific Experiment:

Circle the characteristic that your group has chosen to test: Total Water Absorbency OR Strength When Wet

  1. State a testable question for the assigned characteristic you are testing (total water absorbency or strength when wet).

Question:

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2. After examining the two brands of paper towels, you should have some specific information/insights (“educated guess”) as to the answer to your question. Write this answer as your hypothesis.

(Note: In your hypothesis, provide the information you used to make the “educated guess”):

Hypothesis:

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3. Design an appropriate experiment for the characteristic and write out detailed instructions (in the form of step-by-step statements; 1., 2., 3., etc.) describing how your group will carry out each experiment. A good way to approach this task is to assume that someone else should be able to duplicate the experiment by reading your group’s instructions. Remember to eliminate as many unwanted variables as possible.Note: Be certain to give step-by-step instructions. Do not use paragraph form. Numbered and appropriately labeled diagrams may also be used to visually clarify the instructions. Make a rough draft of this section on another sheet of paper. When you finish designing an experiment, discuss your plans with the instructor before proceeding. On the basis of this discussion, certain aspects may need to be redesigned. Then transfer the revised, final version to this section below.

Experimental Design:

4. Think ahead to the collection of the data, and design an appropriate table where you will record your data (see the example below). If numerical data are collected, calculate and present an average NOTE: You will have a maximum of five towels of each brand for your experiment (i.e. 10 total towels, 5 of each brand). Therefore, plan carefully before you begin.

Example: Note that a descriptive title is provided, each column is clearly labeled, and appropriate units (e.g. milliliters; ml) are indicated.

Average Total Water Absorbency for Two Brands of Paper Towels
Brand / Water Absorbed Trial One(ml) / Water Absorbed Trial Two(ml) / Average Total Water Absorbency (ml)
A / 15 / 16 / 15.5
B / 13 / 14 / 13.5

Data Table:

5. After the data are presented in a tabular manner, develop a way of visually presenting the average datavalues in graphical form (your graph should only contain TWO bars). Remember the class discussion regarding how to construct a graph and the various considerations including the independent and dependent variables, scale, title, units, type of data (continuous or discontinuous), axis labels, and use of a legend/key.

Graph of Data:

6. Analyze your group’s data and draw a conclusion. Remember, the conclusion should simply answer the question posed at the beginning of the process.

Conclusion:

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7. Reflect on the design of your group’s experiment. Come up with two specific changes you would make if starting over again, and make certain that you explain how the changes will results in an improved design.

Experiment Design Improvements:

First Improvement: ______

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Second Improvement: ______

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D. Review Questions

1. What is the purpose/function of the scientific method?

2. What are the general processes (i.e. steps) of the scientific method?

3. What is the distinction between a testable question and a hypothesis?

4. What considerations/strategies should be taken when presenting the experimental design (i.e. the directions for conducting your experiment)?

5. What is an independent variable? What was the independent variable in your experiment?

6. What is a dependent variable? What was the dependent variable in your experiment?

7. State at least 2 control variables and one confounding variable in your experiment.

8. Which variable(s) (i.e. dependent and/or independent) is/are typically presented on the X-axis of a graph? The Y-axis?

9. How do you determine the scale increments when developing a graph?

10. Given a set of data, describe how you would present the data in graphical form?

11. In your opinion, would it be appropriate to combine data from different research groups?

12. Why should conclusions from experiments be stated in a conservative manner (i.e. avoiding the use of terms such as “prove”)?

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