Contributed by: Connecticut Academic Performance Test (CAPT)
There is one example 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.
A group of students prepared a vinegar-and-water solution to simulate
acid rain. After determining its pH, they poured the solution through
cups that contained various earth materials (sand, potting soil and
crushed limestone). The students measured the amount of solution that
percolated (passed) through a hole in the bottom of each cup in a
set amount of time, and they tested the pH of the drippings.
The results of the group's experiment are shown in the following table.
| Earth Materials |
pH of "acid rain" before percolation |
Amount of "acid rain" percolated in 3 minutes |
pH of percolated "acid rain" |
| sand |
3.0 |
30ml |
3.5 |
| potting soil |
3.0 |
20ml |
3.5 |
| crushed limestone |
3.0 |
90ml |
5.0 |
| all three Earth materials |
3.0 |
50ml |
5.5 |
Question 1 - Event Score = 3
What is one problem that this group is investigating? State the problem
in your own words.
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Component
|
Score
|
Commentary
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Question 1
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(3)
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This response correctly states both problems that
are being investigated. In each case the independent variable
("earth materials") and dependent variables ("acidity of acid
rain as it is filtered through" and "how long the acid rain
solution takes to seep through") are correctly identified. |
Question 2 - Event Score = 3
What are the variables that need to be controlled in this experiment?
Explain why it is important to control them.
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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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(3)
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The response discusses several variables that
are important to control ("amount of water and material" and
"amount of time"). The importance of controlling these variables
is discussed. |
Question 3 - Event Score = 3
Do you have enough information to replicate this group's experiment?
If you think you do, tell what information you have. If you think
you do not, tell what other information you would need.
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Component
|
Score
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Commentary
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Question 3
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(3)
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This response is correct and elaborate. It identifies
several pieces of information that are needed to replicate the
experiment ("how much earth materials", "how much acid rain"
and, "What ratio the water and vinegar were in"). |
Question 4 - Event Score = 3
The group concluded that sand and potting soil have the same ability
to neutralize acidity because in each case the pH went from 3.0 to
3.5. Based on this group's experiment and results, do you think the
group's conclusion is valid? Explain why or why not.
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Component
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Score
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Commentary
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|
Question 4
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(3)
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The response is correct. It correctly explains
that the results can not be validly compared because of the
different amounts of acid rain percolated. The explanation
is elaborated. |
Go to Next Student Work
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