As an assessment of prior investigations working with red cabbage juice
as an indicator, the teacher asked students to see what would happen when
they blew through a straw with BTB (bromthymol blue) solution. Students
were given BTB, water, cups, and straws. They designed and recorded their
own procedures and observations and were asked to explain what happened.
When they were done, they conducted a further exploration with vinegar and
BTB solution to test their initial conclusion that the color change of BTB
from blue to yellow indicated the presence of an acid.
| This sample of student work was produced under the following
conditions: |
| alone |
in a group |
| in class |
as homework |
| with teacher feedback |
with peer feedback |
| timed |
opportunity for revision |
The students were asked to re-write steps 8, 9, and 10 of their original
procedure as a second experiment.
 a
Physical Sciences Concepts: The
student produces evidence that demonstrates understanding of properties
of objects and materials, such as similarities and differences in…color…[and]
the ability of materials to react with other substances….
The data table indicates recognition of a change of color and the
ability of materials to react with different substances.
In the conclusion, the students state, “The color of the liquid
changed, so there was a chemical change.”
 In light of ,
the students’ connection of color change to acid/base determination
is evidence of an understanding that a chemical reaction has occurred
between the materials.
 a
Scientific Connections and Applications:
The student produces evidence that demonstrates understanding of big
ideas and unifying concepts, such as…cause and effect.
The students recognized that the color change was caused by the addition
of certain chemicals and that similar chemicals will have similar
effects.
|
 |
 b
Scientific Thinking: The
student uses concepts from Science Standards 1 to 4 to explain…observations
and phenomena.
The students applied an understanding of a,
properties of objects and materials, and a,
cause and effect, to explain the results of the experiment.
e
Scientific Thinking: The
student identifies problems, proposes and implements solutions, and
evaluates the accuracy, design, and outcomes of investigations.
 The students developed
another experiment, hypothesized, and evaluated the outcome based
on previous knowledge and the results of both experiments.
 a
Scientific Tools and Technologies: The
student uses tools…to gather data. |
 |
Use of the BTB in the
students’ follow-up experiment is evidence of accurate use of BTB
as a tool.
 “…the BTB
was an indicator…” demonstrates understanding that indicators
can be used to detect acids and bases.
.gif) |
 a
Scientific Communication:
The student represents data and results in multiple ways, such as…tables…drawings,
diagrams, and art work.
 Both the table
and the student’s color diagram clearly show the results of
the experiment.
c
Scientific Communication: The
student communicates in a form suited to the purpose and audience,
such as writing instructions that others can follow.
Throughout the work, appropriate scientific vocabulary is applied,
such as accurate use of “interaction”, “chemical
change”, “exhaled”, “carbon dioxide”,
and “indicator”.
|
 |
The procedure in the
students’ follow-up experiment clearly describes the steps of the
experiment in a way that would allow replication by another elementary student. |
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