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ME405: Wet-Dry Bulb Hygrometers: Measuring Relative Humidity and Apparent Temperature
Rubric
Contributed by: Council of Chief State School Officers (CCSSO)

Item #1

Item Description: A thermometer that is used to measure the temperature of a hot gas is calibrated in boiling water (the temperature of boiling water at 1 atm = 212.). Use the following information to calculate the actual temperature of the hot gas. Make sure to show all work.
  • The temperature of the boiling water according to the thermometer = 215.

  • The actual temperature of the boiling water = 212.

  • The temperature of the hot gas according to the thermometer = 375.

  • The actual temperature of the hot gas = _______.
This event assesses the student's understanding of thermometer calibration and correction factors. It assesses the ability to apply correction factors to thermometer readings in order to calibrate correctly.


Content Definition: All thermometers can have a defect in production that causes them to read an incorrect temperature. Not all thermometers are the same. In order to get precise readings from a thermometer, a correction factor must be determined for the thermometer. A correction factor can be determined by simply subtracting the actual temperature of the medium from the recorded temperature. The difference is the correction factor. If the correction factor is positive, it must be subtracted from the thermometer reading to get a correct reading. If the correction factor is negative, then it is added to the reading to get a correct reading. The correct temperature for this problem is 372.


Scoring Parameters: Scores are based on the student's ability to:
  • Understand the concept of calibration in reference to thermometers. Shows work.

  • Calculate actual temperatures.


Score Level Descriptions:
NS No response or attempt at question.
1 Student shows a limited understanding of calibration or correction factors. Student calculates an incorrect actual temperature, and shows no work.
2 Student shows some understanding of calibration or correction factors. The student calculates an incorrect actual temperature but shows some work done.
3 Student shows adequate understanding of calibration and correction factors. The student calculates the correct actual temperature but shows some incorrect work or no work at all.
4 The student shows a high level of understanding of calibration and correction factors. The student calculates the correct actual temperature and shows all the correct work needed to achieve the correction factor and actual temperature.





Item #2


Item Description: Students will study the 7-day weather log and respond to the question: Predict the noontime air pressure, percent cloud cover, and precipitation if the air temperature is 86 and relative humidity is 97%. Explain how you arrived at the conclusion.

Table 4
Day
Relative humidity (%)
Air temperature
()
Air pressure (inches of mercury)
Cloud cover (%)
Amount of precipitation (inches)
1
6
75
28.95
40
0
2
98
85
28.30
100
1.5
3
30
77
29.01
25
0
4
40
75
29.50
0
0
5
55
78
29.20
30
0
6
60
79
28.95
50
trace
7
95
85
28.25
100
1.3



Content Definition: There are weather factors in this item that are clearly interacting. When relative humidity is low: air temperature, cloud cover, and precipitation are also low; where as air pressure is high. When relative humidity is high: air temperature, cloud cover, and precipitation are also high; where as air pressure is low. The table shows a pattern with air temperature and relative humidity that can be used to predict the air pressure, precipitation, and cloud cover under given situations. In this problem, since the air temperature is rising to 86 degrees and the relative humidity is also rising to 97%, the pattern indicates that cloud cover will increase (most likely 100%), air pressure will decrease, and the amount of precipitation will increase (to between 1 and 2 inches).


Scoring Parameters: Scores are based on the student's ability to:
  • Note how changes in temperature, relative humidity, cloud cover, pressure, and precipitation appear to have influences upon each other.

  • Predict likely weather and explain the prediction according to other weather conditions.

  • Develop a response:
    • Low level-state a concept related to the question with few terms and concepts clarified, few examples from the weather log, few connections made between relative humidity, temperature, cloud cover, precipitation, air pressure, and predictions for noontime conditions.

    • High level-state a correct concept related to the question with many terms and concepts clarified, many examples from the weather log, and many connections are made that elicit accurate predictions for noontime conditions.


Score Level Descriptions:
NS No response is given.
1 The student shows a limited understanding of interaction between weather factors in predicting the weather. The student makes a prediction that may be correct or not, but gives no explanation for the prediction; OR describes something about weather conditions from the table, but gives no prediction. Response has little or no development (see parameters).
2 The student shows some understanding of the interaction between weather factors in predicting the weather. The student makes a prediction that may or may not be correct AND describes something about weather conditions from the table. Response has at least low level of development.
3 The student shows an adequate understanding of the interaction between weather factors in predicting the weather. The student makes a correct prediction AND reasons on the grounds that weather factors in the table are interacting with each other to cause the conditions. Response has a moderate level of development.
4 The student shows a high level of understanding of the interaction between weather factors in predicting the weather. The student makes a correct prediction and reasons on the grounds that a pattern exists in the table where when relative humidity and air temperature both rise, the cloud cover and precipitation increase while the air pressure decreases. Response has a high level of development.

 


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