Grade 912 Performance Task
Developed by: New York State Education Department (NYSED)
University of Buffalo and NORC (1991, revised 1993)
Part A
Introduction:
This laboratory test presents a problem and lists
materials available to you. Your task is to design a strategy
for solving this problem. Please record all your answer on these
sheets. You will have 30 minutes to plan and design an experiment
to solve the problem.
Problem:
One of the tests that scientists can use to identify
a substance is to measure its index of refraction through the
Snell's Law equation. (The index of refraction is equal to the
ratio of the sine of the angle of incidence to the sine of the
angle of refraction.)
Suppose that you are working for the Consumer Protection
Agency and your job is to determine whether the index of refraction
of a sample of Corn Syrup meets Federal standards of 1.55. You
have been given the data collected by a colleague, and your job
is to analyze the ray diagram and determine whether the index
of refraction is 1.55 (+ or  5%).

Under the heading PROCEDURE list in
order the steps of the procedure you will use to solve the
problem. You may include a diagram to help illustrate your
plans for the experiment. Include any safety procedures you
would follow.

Construct a DATA TABLE or indicate
any other method that you could use to record the observations
and results that will be obtained.

At the end of the 30 minutes, your answer
sheet for Part A will be collected.
PLEASE NOTE: In Part A, you are NOT to proceed
with any part of the actual experiment. You are just to plan and
organize a way to investigate the problem.
Materials:
 Corn Syrup A
 semicircular dish
 graph paper
 calculator
 protractor
 pencil
 straight pins
 cardboard
 ruler
 graph paper
PART A  Experiment Design
Organize your experiment design under the following
headings:
PROCEDURE and DATA TABLE.
Use the front and back of the sheets if necessary.
PROCEDURE
DATA TABLE (For results and observations)
Part B
Introduction:
You will have 50 minutes to complete this part. You have been provided
with a detailed Procedure (see below) which you are to follow. Record
your work for Part B on the answer sheet under the appropriate headings.
Problem:
One of the tests that scientists can use to identify
a substance is to measure its index of refraction through the Snell's
Law equation. (The index of refraction is equal to the ratio of
the sine of the angle of incidence to the sine of the angle of refraction.)
Suppose that you are working for the Consumer Protection
Agency and your job is to determine whether the index of refraction
of a sample of Corn Syrup meets Federal standards of 1.55. You have
been given the data collected by a colleague, and your job is to
analyze the ray diagram and determine whether the index of refraction
is 1.55 (+ or  5%).
 Perform the experiment by following the steps outlined in the
procedure.
 Under the heading RESULTS/OBSERVATIONS record the data
collected in the experiment. Use statements, descriptive paragraphs,
and tables of data where appropriate.
 Under the heading CALCULATIONS show all equations and
calculations used.
 Construct a GRAPH that shows the relationship between
the variables measured.
 Under the heading CONCLUSION give an interpretation of
your results.
 At the end of the 50 minutes, your answer sheets will be collected.
Materials:
 Corn Syrup A
 semicircular dish
 graph paper
 calculator
 protractor
 pencil
 straight pins
 cardboard
 ruler
 graph paper
Procedure:
 The ray diagram shows the angles of incidence and refraction
for Corn Syrup A when a light ray was directed at the semicircular
container.
 Measure and record the values for the incident nd refracted
angles from the ray diagram.
 Compute the vlues for the sine function for these angles.

Plot the values for sin i against the
values for sin r and determine the index of refraction
from the slope of the graph.
 Determine whether the index of refraction is within the limits
of:
1.55 (+ or  5%). Show all calculations.
 Record your answer under Conclusion.
Data Table:
Angle i

Sin i

Angle r

Sin r

20 degrees 



25 degrees 



30 degrees 



35 degrees 



40 degrees 



45 degrees 



50 degrees 



55 degrees 



65 degrees 



Ray Diagram
CALCULATIONS
GRAPH
CONCLUSION
Based on a graphical analysis of the data you collected
in this experiment, discuss your conlcusion as to whether the index
of refraction of Corn Syrup A meets Federal standards of 1.55. Be
certain to explain how you used your data to arrive at this conclusion.
