Appendix D: Assessment and Evaluation - Samples

Sample 4: Grade 12

Topic:

Prescribed Learning Outcomes:

Transducers (Electrical/Thermal)

It is expected that students will:

• construct and calibrate a thermal transducer or an electrical transducer
• identify and describe common situations in which electrical transducers are used
• identify and describe common situations in which thermal transducers are used
• use calibration values to solve common problems involving electrical and thermal transducers

Overview

The teacher planned a unit in which students learned about designing, constructing, and calibrating transducers. The teacher evaluated students' problem-solving skills and their understanding of transducers.

Planning for Assessment and Evaluation

• The teacher presented the class with a mood ring and asked them to explain how it worked. Following the discussion, the teacher asked questions about transducers:
  • What makes a good transducer in most cases? (A small sample of a system's energy is converted to a more usable form.)
  • What physical relationships can be used to derive quantity? (Liquid-in-glass thermometer­relationship of surrounding temperature affects the volume of liquid enclosed.)
• The teacher asked students to work in groups to brainstorm examples of transducers. In each case, they attempted to identify the relationship that allowed the transducer to accurately indicate the quantity in question.
• As a class activity, the teacher demonstrated several basic transducers and took data to enable a proper calibration. The teacher then guided students through the steps of creating a calibration curve and a calibration constant if appropriate (when slope is constant).
• Students then conducted several investigations by setting up transducers and using them to take values. Students calibrated each transducer and discussed where such a transducer would be useful and why.
• The teacher explained how accelerometers can be used to determine frequency of vibration and plane of vibration with the aid of an oscilloscope. Students then set up an accelerometer to monitor a vibrating system. The class discussed other significant types of transducers (e.g., multimeters, pitot tubes) and the relationships that allow them to indicate quantities.
• The teacher then provided students with problems involving calibration constants and asked them to construct appropriate transducers.
• The teacher reviewed the unit activities, emphasizing the distinctions between energy converters and transducers. Key points included:
  • descriptions of transducers
  • common applications
  • identification of energy type and units in the various systems
  • vocabulary
  • problem-solving strategies
• The teacher presented the following problem: Design an energy conversion system that uses transducers on two different energy forms in order to obtain information that determines as directly as possible the efficiency of the energy conversion.
• The teacher then presented a sample solution. A mechanical transducer provides mass data, and a thermal transducer provides temperature difference data. This permits calculation of thermal energy loss. The energy conversion to mechanical work is obtained from a strain gauge measuring force, and distance data permits calculation of work done. The efficiency of the conversion can then be calculated.
• The teacher led a discussion of how the conversion system could be improved, either in terms of transducers used, or their application in determining the efficiency of the energy conversion.
• Groups of students each selected an energy conversion system, identified the transducers required, described the information to be collected, and explained how it would be used. Following the approval of the teacher, they constructed their systems, gathered data, and determined the efficiency of the conversions.

Defining the Criteria

Problem Solving

To what extent does the student:

• engage in solving the problem
• use appropriate background knowledge
• use effective problem-solving processes
• represent solutions to the problem

Understanding Transducers

To what extent does the student:

• identify transducers
• identify principles operating in various transducers
• recognize which transducer is appropriate for a particular circumstance
• determine an appropriate method for calibrating a particular transducer
• suggest improvements to transducer applications
• identify limitations of particular transducers

Assessing and Evaluating Student Performance

Problem Solving

Understanding Transducers

The teacher used a performance scale to assess and evaluate students' understanding of transducers.

Criteria	Rating
recognizes the application of transducers	5     4     3     2     1
identifies energy conversions	5     4     3     2     1
calculates energy with information from the transducers	5     4     3     2     1
calculates efficiency	5     4     3     2     1
identifies sources of energy loss	5     4     3     2     1
suggests improvements to the transducer applications	5     4     3     2     1

Key:

5­Excellent: criterion met to an exceptional or unusual degree.
4­Very good: criterion met in a very effective way.
3­Good: criterion met in a competent and effective way.
2­Satisfactory: criterion met, but with considerable room for improvement.
1­Minimally acceptable: criterion met to some extent.
0­Not evident: criterion not met.

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Last Modified: April 1, 1998.
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