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Contributed by: Connecticut Academic Performance Test (CAPT)
Item 1
This item assesses students' understanding of the need to conduct
a controlled experiment when investigating the effect of one variable
on another. The purpose of this experiment is to determine which
form of salt, table salt or rock salt, is better for melting ice.
In this group's experiment the third beaker containing only ice
water serves as a control. The control is used to compared the freezing
point of the ice without either type of salt. (Students may note
that a control is not necessary for comparing the two salts.)
CAPT Framework
Experimentation: Design and conduct appropriate experiments.
Item 2
This item assesses students' understanding of what constitutes a
complete and appropriate experimental design. In this case, students
do not have all of the information that they need to replicate the
experiment. Some of the additional information that students would
need to know includes how much of each type of salt, ice, and water
were used, the initial temperature of the contents of the beakers,
the temperature of the surroundings, how well the components were
mixed, etc.
CAPT Framework
Experimentation: Design and conduct appropriate experiments.
Item 3
This item assesses students' abilities to draw conclusions based
on data and to consider the validity of the conclusions. While more
ice appears to have melted in the beaker containing rock salt, the
conclusion should be strongly questioned. It is uncertain whether
important variables have been controlled such as the initial mass
of the ice, salt, and beakers, the exposed surface of the ice cubes,
and the distribution of the salts. The difference in the mass of
the two beakers and their contents at the end of the experiment
is not very large. In addition, some of the salts may have been
poured off with the melted water.
CAPT Framework
Experimentation: Make, record and interpret observations/Draw conclusions
and discuss their validity.
Item 4
This item assesses students' understanding of what constitutes a
complete and appropriate experiment. In this case, the group of
students could have improved their experiment by determining the
initial mass of the beakers, ice and salts to make sure they were
equal and by controlling other important variables. They could have
measured the volume of the water poured off. In addition, an appropriate
control could have been used and the group could have carried out
the experiment several times.
CAPT Framework
Experimentation: Design and conduct appropriate experiments.
Sample Student Responses for Experimentation Questions: "Ice
Cold"
There are several examples for each score point ranging from 3
down to 0. Explanations of the scores were written by staff from
the Division of Teaching and Learning at the Connecticut State Department
of Education who conducted training and scoring of field tested
events.
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Component
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Score
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Commentary
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Question 2
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(1)
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This response identifies two relatively important
pieces of information ("what the container with the ice water
in it is made out of," "the temperature of the room they are
conducting the experiment in"). While this response contains
some elements of a proficient response, it is incomplete. |
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Component
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Score
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Commentary
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Question 2
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(1)
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This response correctly identifies some of the
important information given in the experiment but fails to
recognize that information is needed if the experiment is
to be replicated. |
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