BOX 3-9 Sample 5: KELLY

Describe your first experiment:

B.S. + C.C. + H2O

What happened?

heat, bubbles, color change.

What can you conclude?

Describe your second experiment:

C.C. + phenol red solution

What happened?

turned hot, pink, boiled

What can you conclude?

Is water + C.C. or phenol + C.C.

What do you think causes the heat?

Water + C.C.

Areas for Additional Practice

√ planning experiments that address a particular question

√ designing controlled experiments

√ keeping clear, detailed records of plans, results, and conclusions

√ drawing conclusions from experiment results

√ using scientific notation to record experiments and results

Kelly at first substitutes water for phenol red. Her observations of the reaction are perceptive, but she is unable to reach a conclusion. She then chooses to mix calcium chloride and phenol red solution. While technically the variables are controlled between this experiment and the original reaction—baking soda becomes the test variable—Kelly's conclusion is that water and calcium chloride, or phenol red and calcium chloride, cause the heat. These conclusions are not justified by her experiments nor is her final conclusion that water plus calcium chloride cause the heat. Her recording is minimal, though she does make an attempt to use chemical notation.

SOURCE: Barber et al. (1995).

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