Work Sample & Commentary: An Application of Eratosthenes’s Method
The task
During a laboratory lesson, students determined the circumference of a classroom globe using Eratosthenes’s Method. After comparing their experimentally determined circumference with the accepted value for the circumference, students determined their percent error and identified possible sources of error. Finally, students were asked to apply this method to a novel situation—determining the size of the Unisphere in Flushing Meadows Park.

Circumstances of performance
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

This work sample illustrates a standard-setting performance for the following parts of the standards:
e Scientific Thinking: Identify problems; propose and implement solutions; and evaluate the accuracy, design, and outcomes of investigations.
a Scientific Tools and Technologies: Use technologies and tools.
a Scientific Communication: Represent data and results in multiple ways.
d Scientific Communication: Explain a scientific concept or procedure.
e Scientific Communication: Communicate in a form suited to the purpose and the audience.


What the work shows

e Scientific Thinking: The student identifies problems; proposes and implements solutions; and evaluates the accuracy, design, and outcomes of investigations.
In the procedure, the student describes a proposed solution to the problem of determining the Unisphere’s size.
In the answer to question 3 in the conclusion, the student evaluates the investigation and identifies possible sources of error.

a Scientific Tools and Technologies: The student uses technologies and tools…to observe and measure objects…directly, indirectly and remotely, with appropriate consideration of accuracy and precision.
In the diagrams, the student provides evidence of proper use of a ruler, a measuring tape, and a protractor.
Data collected with the tools was subjected to appropriate consideration of accuracy by the calculation of the percent error for each experimental value.

a Scientific Communication: The student represents data and results in multiple ways, such as numbers, tables, and…diagrams; technical and creative writing; and selects the most effective way to convey the scientific information.
The student presented the procedure in writing and the data in two diagrams. Choosing to use diagrams to support the written procedure demonstrates selection of the most effective way to convey scientific information.
In the data table, the student shows consideration of accuracy by calculating the percent error for each of the experimental values.

d Scientific Communication: The student explains a scientific concept or procedure to other students.
The procedure is explained and illustrated clearly.
The answer to question 2 in the conclusion addresses variables that would affect the outcome of the investigation.

e Scientific Communication: The student communicates in a form suited to the purpose and the audience, such as by writing instructions that others can follow….
The clear, concise, and logically sequenced procedure, especially as supported by labeled diagrams, demonstrates understanding of Eratosthenes’s Method and could be easily replicated by others.