Appendix D: Assessment and Evaluation - Samples

Work in Mechanical and Fluid Systems

It is expected that students will:

• convert from one set of work units to another

Energy (Thermal Systems)

It is expected that students will:

• identify various units used to measure energy in thermal systems
• convert values from one system of units used in a thermal system to another

Resistance (Fluid Systems)

It is expected that students will:

• identify various units used to measure resistance in a fluid system

Overview

The teacher planned a unit on measurement. Students reviewed measurement concepts and learned about unit conversion. The teacher evaluated students' skills in converting units and, specifically, their abilities to:

• identify units
• determine conversion factors
• apply unit conversions

Planning for Assessment and Evaluation

• The teacher asked students the following questions to find out what students knew about measurement: What things do people measure? For what purposes do people measure things? The teacher then discussed relevant aspects of the history of measurement, and guided students in identifying the conditions or requirements of standards (e.g., universally accepted, readily reproducible).
• Students were asked to group various units into systems. The teacher then had students develop units for area, value, speed, and others that were familiar to them.
• The teacher gave students an overview of the relationships between units within a system and between systems. The teacher then asked students how to convert within a system (e.g., millimetres to metres). In groups, students were asked to explain how they would use metric tables to perform conversions. Then students were asked how to convert between systems (e.g., feet to metres). The teacher explained about precision and discussed with students its importance in everyday situations. (e.g., How much water do you need to fill a swimming pool of a given size? Which size of bolt will fit a particular nut?)
• The teacher set up a number of stations with pencil-and-paper conversion questions and problems, all of a practical nature. (e.g., Why don't stores sell milk in cubic metres? Why isn't the distance to the next town measured in centimetres? Measure the area of this table and state a reasonable value for the uncertainty.) Students rotated from station to station answering the questions.
• To facilitate students' understanding of the basis for conversions, the teacher summarized the concept of fundamental units (mass, length, and time).
• Each student recorded, in both imperial and metric units, her or his height, arm length, wrist circumference, and the force exerted by one hand or foot. Using this information as a model, the teacher asked students to construct charts with headings such as Quantity, Units, and Fundamental Units. As they encountered different measurements, students entered the new information on their charts.
• The teacher reviewed the methods of expressing quantities in fundamental units as a means of assuring essential equivalence, and reinforced the concept of estimation. Key points included:
  • techniques of estimation
  • self-metric measures expressed in fundamental units
  • consequences of differences in unit size
  • efficiency of using conversion factors
• The teacher asked students to select one of the following activities:
  • Using a programmable calculator, derive and store the conversion factor for each of the unit conversions encountered in this program of study.
  • Develop a computer program that converts specified input measurements into alternative units (including fundamental units) and provides conversion factors.
  • For specified unit conversions, develop efficient conversion factors and their reciprocals.
• The teacher observed students as they developed conversion procedures, designed appropriate programming steps and routines, calculated relevant factors, and confirmed their proposals.

Defining the Criteria

Identifying Units

To what extent does the student:

• recognize the appropriate units within a defined system
• use consistent units within a system
• make an estimation of unit conversion

Determining Conversion Factors

To what extent does the student:

• correctly determine the conversion of each element in the unit
• simplify the conversion
• correctly determine the reciprocal conversion
• correctly calculate the conversion factors

Applying Unit Conversions

To what extent does the student:

• estimate the magnitude of the converted unit
• ensure that consistent units are used in measurements
• apply the appropriate conversion factor
• compare his or her estimate to the calculated value

Assessing and Evaluating Student Performance

The teacher used a scale to assess students' conversion of units.

Criteria	Rating
	Always	Sometimes	Not Observed
recognizes the appropriate units within a defined system
uses consistent units within a system
makes an estimation of unit conversion
correctly determines the conversion of each element in the unit
simplifies the conversion
correctly determines the reciprocal conversion
correctly calculates the conversion factors
estimates the magnitude of the converted unit
applies the appropriate conversion factor
compares her or his estimate to the calculated value

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Last Modified: April 1, 1998.
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