Circle Lab
Purpose: To explore experimental design
Introduction: Correctly writing lab reports will enhance your scientific communication skills. We will use this Circle Lab to model proper techniques for sharing information by focusing on the Conclusion section of a lab report. Your conclusion will have three parts: a restatement of the purpose (which answers the question, "Why did we do this activity?"), a brief description of the results of the activity and what you learned (do not include the procedures), and possible sources of error (be specific, for example, "human error" is too vague). Remember that the conclusion is a narrative that is written in complete sentences.
Materials: Metric ruler, meter stick, string, and objects with a circular surface (can of soup, bicycle tire, lids, drinking glass, etc.)
Procedure:
Assemble six objects that have a circular surface. Carefully measure the diameter of the circular surface of each object. Measure the value to the nearest hundredth of a centimeter and record the value in Table 1.
To measure the circumference of each object, cut a long piece of string and wrap it around the circular surface of the object. Use the metric ruler or meter stick to measure the length of the string that corresponds to the circumference of the object. Since this method of measurement tends to increase error, measure to the nearest tenth of a centimeter. Record the value in Table 1.
Make a graph using the measured quantities circumference and diameter. Title your graph Circumference versus Diameter.
After completing the activity, there will be a short answer assessment where you will answer questions and submit your conclusion.
Data:
TABLE 1
OBJECT
DIAMETER (cm)
CIRCUMFERENCE (cm)



















Use the following questions to prepare for the assessment:
Using your graph, answer the following questions:
What is the independent variable?
What is the dependent variable?
What is the general shape of the graph line?
What general equation is suggested by the graph line?
You will now use Graphical Analysis to calculate the slope of the line. Choose Analyze from the menu. Select Automatic Curve Fit. Select the proper stock function from the list. (Hint: Your answers from question 1 should help you make the proper selection.) Just below the graph you will see the slope value. Remember that the symbol for slope is "M." When you choose OK to get back to the regular graph screen, you will see a little box on the graph. This box also shows the slope value. (Remember that slope is "m.")
If you are unable to use Graphical Analysis, you can also graph your data on paper to determine the slope. Hint: to determine the slope, use the formula m =
Use complete sentences when writing your conclusion. Your conclusion should answer three questions:
"Why did I do this lab (purpose)?"
"What did I learn from doing this lab?"
"What are some errors that may have occurred when I performed this lab?"