Contributed by: Assessment Performance Unit (APU)
Science seen as a practical problem solving exercise led to the
focus on the science processes in the assessment framework. The
category system represents the description of component skills which
pupils need to solve problems. Performing investigations is the
activity represented as a whole and is a synthesis of the other
categories.
An example of a performance investigation question used in the
1981 survey at ages 13 and 15 was "Survival" The question is set
in a context outside the school laboratory. The content includes
such items as tin cans, measuring cylinders and thermometers, which
allow, even encourage, the pupils to model the everyday context
into a science one.
Performing investigations is primarily concerned with the different
pathways taken by pupils between their perception of the problem
and the solution at which they arrive. The pathway taken depends
upon both the problem posed and the individual pupil's knowledge
and skills, as demonstrated in the examples below.
For one pupil- Mark- the problem in "Survival" was to find out
which of two materials got "hotter." To solve it, he cut out two
jacket shapes, one from each material. He started the clock and
subjected each jacket to hot air from the hair dryer for five minutes.
He then felt each jacket and decided that the blanket was warmer.
For another pupil- Ann- the problem was to find out which material
was the better insulator. She determined the rate of cooling when
the two materials were placed around cans of hot water. In doing
this she placed equal areas of material around identically sized
cans. The aspects of performance illustrated by these examples are
summarized in Table 3.
Table 3: Aspects of Performance
Problem formulation-
For both pupils, the first step is the generation of a problem.
Reformulation- deciding what to measure
The next step is to choose the strategy to follow in order to
solve the problem.
Mark
Hold the material in the hand and measure
heat.
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Ann
Wrap the material round cans of hot water
and measure the rate of cooling.
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Planning- setting up conditions
Once the experiment has been operationalized into an experimental
set-up, further decisions have to be taken about the design.
Mark
How much material? Is the hairdryer to be
used?
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Ann
What temperature of water and how much? Which
can(s)?
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Using apparatus and making measurements
When this stage is completed the pupils must carry out their experiment.
Mark
Is the stop-clock to be used to time? Should
the temperature change be judged qualitatively?
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Ann
Should a beaker or a measuring cylinder be
used to measure the volume of the water? How many thermometer
readings are necessary?
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Recording, interpreting and drawing conclusions
These operations lead to the collection and recording of data.
These data have then to be interpreted so that conclusions can be
drawn.
Mark and Ann have answered different questions--they have perceived
the problem as being linked to thermal capacity and thermal conductivity
respectively. Nevertheless each of them has gone through a number
of identifiable stages as outlined in diagrammatic form in Figure
2.
For some pupils progress through the problem-solving chain is
apparently linear. This may not necessarily be the case, however;
they may have made a mental plan, evaluated it and amended it before
putting it into practice. If they consider that their conclusion
is a suitable solution to the perceived problem, their experiment
is complete. However, for other pupils the process of evaluation
may lead them to reject their conclusions and to take further action.
They re-enter the chain and modify their experiment.
The kinds of actions that pupil evaluation can lead to are demonstrated
in Figure 3 by reference to "Survival" and to Mark's and Ann's experiments.
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