administration student task rubric student work technical quality
Snell's Law
Administration Procedures

Grade 9-12 Performance Task
Developed by: New York State Education Department (NYSED)
University of Buffalo and NORC (1991, revised 1993)


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. In this activity, students, as scientists in the Consumer Protection Agency, will determine whether the index of refraction of a sample of Corn Syrup meets Federal standards.

This task assesses students' abilities to develop procedures for investigation, plan for recording and organizing observations and data, make quality observations and collect quality data, create a graph appropriate to the data trend, calculate slope using trigonometric principles, and make conclusions consistent with scientific principles.

This task is designed to take students approximately 80 minutes to complete - 30 minutes for Part A and 50 minutes for Part B.

Overall Task Content Area:

Physical Science

Specific Knowledge Areas:

Transfer of energy

Performance Expectations:

  • conducting investigations
  • using equipment
  • gathering, organizing, and representing data
  • formulating conclusions from investigational data
  • applying scientific principles to develop explanations

National Science Eduation Standards:

8 B PS 3: Transfer of energy: Grades 5-8
3.3 Light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection). To see an object, light from that object emitted by or scattered from it must enter the eye.

12 A SI 1: Abilities necessary to do scientific inquiry: Grades 9-12
1.2 Design and conduct scientific investigations. Designing and conducting a scientific investigation requires introduction to the major concepts in the area being investigated, proper equipment, safety precautions, assistance with methodological problems, recommendations for use of technologies, clarification of ideas that guide the inquiry, and scientific knowledge obtained from sources other than the actual investigation. The investigation may also require student clarification of the question, method, controls, and variables; student organization and display of data; student revision of methods and explanations; and a public presentation of the results with a critical response from peers. Regardless of the scientific investigation performed, students must use evidence, apply logic, and construct an argument for their proposed explanations.

1.3 Use technology and mathematics to improve investigations and communications. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

National Council of Teachers of Mathematics:

NO3: Compute fluently and make reasonable estimates:
Grades 9-12 n. develop fluency in operations with real numbers, vectors, and matrices, using mental computation or paper-and-pencil calculations for simple cases and technology for more-complicated cases
Grades 9-12 o. judge the reasonableness of numerical computations and their results

AL1: Understand patterns, relations and functions:
Grades 9-12 n. interpret representations of functions of two variables

AL2: Recognize and analyze mathematical situations and structures using algebraic symbols:
Grades 9-12 l. use symbolic algebra to represent and explain mathematical relationships

DAP1: Formulate questions that can be addressed with data and collect, organize, and display relevant data to answer them:
Grades 9-12 l. understand the meaning of measurement data and categorical data, of univariate and bivariate data, and of the term variable

MEAS2: Apply appropriate techniques, tools, and formulas to determine measurements:
Grades 9-12 r. apply informal concepts of successive approximation, upper and lower bounds, and limit in measurement situations

PS4: Monitor and reflect on the process of mathematical problem solving:
Grades 9-12

RP3: Develop and evaluate mathematical arguments and proofs:
Grades 9-12

CNX2: Understand how mathematical ideas interconnect and build on one another to produce a coherent whole:
Grades 9-12

General Instructions to the Teacher:

This task is designed to take approximately 80 minutes to complete - 30 minutes for Part A and 50 minutes for Part B.

Students will be working individually during this exercise.

Students should be ready to work as soon as the period begins. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for "Snell's Law":

At each station students should have:

  • Corn Syrup A (glucose solution)
  • semi-circular dish
  • straight pins
  • polar co-ordinate paper
  • cardboard calculator
  • metric ruler
  • protractor
  • plain paper

Advance Preparation:

Note: Students will not have to trace the rays through the syrup; the tracings will be supplied to them. The ray diagram is in the student booklet. They will only be interpreting the data. The equipment is made available to help them in Part A.


  • Be careful.
  • Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.





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