9th Grade Performance Task
Developed by: RAND Corporation (RAND)
Stanford University and the Far West Laboratory, 1994

The Alpine Outdoor Clothing Company has asked you, as skilled science students, for information on the following problem:

Given a choice of jackets made from three different materials, which one would do the best job of slowing down the loss of body heat?

Read through all of the instructions BEFORE beginning this experiment!

Complete the following steps when directed to do so by your instructor.

TRIAL 1

1. Wrap the empty can in Fabric A, place it in the plastic bag (with the opened end facing up), and put the two rubber bands around the bag to hold it in place. Make the bag fit tightly, so there is no air space between the bag and the can (see Figure 1 on page 2).
   
   
2. Add roughly equal amounts of ice and water from a faucet ("Tap Water") to the large plastic container so that it is nearly full (see Figure 2 on page 2).
   
   

   

3. Place 200 ml of "Warm" water into the can wrapped in Fabric A.
   
   
4. Place the thermometer in the can and seal the top of the bag around it (see Figure 3 above).
   
   
5. Place the setup shown in Figure 3 into your ice water bath (see Figure 4 above). Be careful not to let any of the water from the ice water bath get inside the plastic bag.
   
   
6. Check the temperature of the warm water. When it is 37 degrees Celsius (between 35 degrees and 39 degrees is acceptable), record this as your starting temperature on your Student Data Sheet.
   
   
7. Read the temperature every 30 seconds for five minutes (300 seconds) and record this information on your Student Data Sheet as you go.
   
   
8. Calculate the total change in temperature and the rate of cooling and record these numbers in the appropriate spaces on your Student Data Sheet.
   
   
9. Remove the setup from the ice water bath. Remove the thermometer, water, and fabric "sock" from the can. If necessary, dry the inside of the plastic bag.
   
   

   TRIAL 2

10. Repeat step 1 using Fabric B.
    
    
11. Place 200 ml of "Warm" water into the can now wrapped in Fabric B.
    
    
12. Place the thermometer in the can and seal the top of the bag around it (see Figure 3 on page 2).
    
    
13. Place the setup shown in Figure 3 into your ice water bath (see Figure 4 on page 2). Be careful not to let any of the water from the cold water bath get inside the plastic bag.
    
    
14. Watch the temperature, and try to begin timing just when the temperature reaches 37 degrees Celsius (between 35 degrees and 39 degrees is acceptable). Record the starting temperature in the appropriate space on your Student Data Sheet.
    
    
15. Repeat steps 7 through 9 as done in Trial 1.
    
    

    TRIAL 3

16. Repeat step 1 using Fabric C.
    
    
17. Place 200 ml of "Warm" water into the can now wrapped in Fabric C.
    
    
18. Place the thermometer in the can and seal the top of the bag around it (see Figure 3 on page 2).
    
    
19. Place the setup shown in Figure 3 into your ice water bath (see Figure 4 on page 2). Be careful not to let any of the water from the ice water bath get inside the plastic bag.
    
    
20. Watch the temperature, and try to begin timing just when the temperature reaches 37 degrees Celsius (between 35 degrees and 39 degrees is acceptable). Record the starting temperature in the appropriate space on your Student Data Sheet.
    
    
21. Repeat steps 7 through 9 as done in Trial 1.
    
    

Table 1. Cooling Trial Temperatures

Table 2. Summary

Note: The results on this Sample Data Sheet are from an experiment similar to the one you performed, except that measurements were taken every 60 seconds instead of every 30 seconds.

Table 1. Cooling Trial Temperatures

Table 2. Total Change in Temperature

TEAR OFF THIS PAGE

Read through this table carefully, and use it to help you write answers that are CLEAR, PRECISE, and COMPLETE.

Before starting, make sure you have the following materials: 1 Sample Data Sheet, 1 ruler, 1 ordinary pencil, and 1 set of colored pencils (minimum 3).

1. Graph the results of Trials 1, 2, and 3 only as given on the Sample Data Sheet. Create a line graph on the grid below. Your graph should display data from these three trials on a single set of axes. Data from each trial should be displayed in a different color. YOU WILL BE GIVEN 15 MINUTES TO COMPLETE YOUR GRAPH. (If you finish your graph sooner, go on to the next question.)
   
   

   Title: ________________________________________________________________

   

2. Looking at your graph, describe how the rate of cooling changed during each trial. Remember that your answers should be clear, precise, and complete.
   
   

   a) Trial 1:

    

    

   b) Trial 2:

    

    

   c) Trial 3:

    

    

3. Temperature is measured in degrees Celsius. Heat is measured in calories. One calorie is the energy gained or lost by 1 ml of liquid water when its temperature rises or falls by 1 degree Celsius. For example, if 2 ml of water rose 3 degrees in temperature (delta T = 3 degrees), then 6 calories would be gained. If 5 ml of water fell 2 degrees (delta T = -2 degrees), then 10 calories would be lost. In the box below, write a formula for heat energy lost in calories.
   
   

   If Q is the heat energy lost in calories, and delta T is the total change in temperature in degrees Celsius (see Table 2 on your Sample Data Sheet for an example of delta T), and V is the volume in ml, then Q = ________________________ (complete the equation using delta T and V)

   Using this formula, calculate the heat lost by the water in the can for each of the 6 trials. Be sure to calculate the total heat lost during the five minutes when measurements were taken for each trial.

   Complete the following table as you do your calorie calculations:

   Table 3: Heat loss calculations

   Trial	Fabric	V	delta T	Q
   1	A
   2	B
   3	C
   4	None
   5	None
   6	None

4. a) Which of the six trials showed the greatest total change in temperature?
   
   

    

   b) What was the amount of that temperature change?

    

5. a) Which of the six trials showed the greatest heat loss?
   
   

    

   b) What was the amount of that heat loss?

    

6. What is a possible reason why different temperature changes were observed in Trials 4 and 6?
   
   

    

    

7. a) Name two trials that you could compare to investigate the effect of volume of water in the can on the rate of cooling.
   
   

   _____________ and ______________

   b) Why did you choose those two trials?

    

    

8. From the sample data, what can you conclude about the effect of volume on rate of cooling? Remember that your answer should be clear, concise, and complete.
   
   

    

    

    

9. a) Now answer this question:
   
   

   Given a choice of jackets made from three different materials, which one would do the best job of slowing down the loss of body heat - Fabric A, Fabric B, or Fabric C?

   ___________________

   b) What evidence is there that this fabric would be the best at slowing down the loss of body heat? Be specific. Consider information on the Sample Data Sheet, your graph, and the tables on this Answer Sheet. You may use graphs or illustrations as part of your answer. Remember that your answer should be clear, concise, and complete.