KSB S1: Factor Investigation

This factor investigation is intended to reveal relationships among food dehydration, temperature and evaporation.

Materials: Apples, slicing tool, knife, fan, heat source (120w bulb), wire mesh, scale, graph paper or spreadsheets (computer optional)

Research Question: How does the thickness of a foodstuff such as an apple affect the rate of drying?

Your laboratory team has been assigned the task of designing and conducting a scientific experiment to determine how quickly apple slices of different thicknesses can dry while retaining their usefulness. Your supplies are:

1 apple, which you are to slice into 1/16", 1/8", and 1/4" slices; a slicing tool such as a knife; a floodlight or heat lamp; wire mesh; a fan; a scale; and graph paper or spreadsheets (computer optional).

You will dry the apple slices over a period of 6 hours, recording your observations as best you can during this time.

Design a table that you will use to record data. The data table should have a title that includes both the independent and dependent variables. Describe the procedure you followed to set up your experiment. This procedure should be written logically and sequentially and presented in paragraph form. Check to see that you have included a clear description of how you collected your data. Use a spreadsheet or graph to plot the data. Look at the information represented by your graph and draw conclusions.

Investigate the effect of thickness on drying time. Take slices of apple that are approximately 1/16", 1/8", and 1/4" thick, weigh them, and place them on a piece of mesh that is heated by a light source. Adjust a fan so that it moves air over the slices continuously. Over a period of two days, collect and plot the data to show weight versus time. Convert the plots to dimensionless weights for each slice thickness. Using what you learned here, compose a paragraph elaborating on the conclusions you draw.

Develop Your Understanding

1. Rewrite the title of your experiment in the form of a declarative statement ("The effect of... on... is..?), rather than in the form of a question ("How does.....?).

2. Make a hypothesis about the problem in the "If....then...." format.

3. What is the independent variable for this activity? (Ask yourself, "Which variable is manipulated?")

4. How many trials are sufficient for this kind of investigation? Since you are completing only one trial, how will you come to a valid/reliable conclusion?

5. What is the dependent variable for this activity? (Ask yourself, "Which variable changes as a result of the manipulation?")

6. Which variables are controlled? (That is, which variables are kept constant?)

7. What will you use as a control for comparison purposes?

8. By convention, the results for which variable should be placed in the X or Y axis?

9. What conclusions do you draw from the data collected? Describe any patterns or trends you see in the data. Does the data support or refute your hypothesis?