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Using the Microscope
Administration Procedures

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


In this activity, students will demonstrate their ability to use a compound light microscope through four procedures: preparing a slide, focusing on a slide under the microscope at both low and high power, and measuring the diameter of an onion cell and slide under 100X magnification.

This task assesses students' abilities to use scientific equipment appropriately and record accurate measurements.

This task is designed to take students approximately 40 minutes to complete.

Overall Task Content Area:

Life Science

Specific Knowledge Areas:

The cell

Performance Expectations:

  • using equipment
  • gathering, organizing, and representing data

National Science Education Standards:

12 A SI 1: Abilities necessary to do scientific inquiry: Grades 9-12
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.

12 A SI 2: Understandings about scientific inquiry: Grades 9-12
2.3 Scientists rely on technology to enhance the gathering and manipulation of data. New techniques and tools provide new evidence to guide inquiry and new methods to gather data, thereby contributing to the advance of science. The accuracy and precision of the data, and therefore the quality of the exploration, depends on the technology used.

12 C LS 1: The cell: Grades 9-12
1.1 Cells have particular structures that underlie their functions. Every cell is surrounded by a membrane that separates it from the outside world. Inside the cell is a concentrated mixture of thousands of different molecules which form a variety of specialized structures that carry out such cell functions as energy production, transport of molecules, waste disposal, synthesis of new molecules, and the storage of genetic material.

(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

MEAS2: Apply appropriate techniques, tools, and formulas to determine measurements:
Grades 9-12 q. understand and use formulas for the area, surface area, and volume of geometric figures, including cones, spheres, and cylinders

PS2: Solve problems that arise in mathematics and in other contexts:
Grades 9-12

General Instructions to the Teacher:

This task is designed to take approximately 40 minutes to complete.

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 "Using the Microscope":

  • Compound light microscope
  • Transparent metric ruler
  • Prepared slide of onion specimen
  • Glass microscope slide
  • Plastic cover slips
  • Dropper bottle with water
  • Pieces of onion bulb
  • Forceps
  • Paper towel or tissue
  • Prepared slide of colored threads

Advance Preparation:

  1. Select a testing area that provides approximately 24" by 36" of working space and a nearby electrical outlet.

  2. Select a compound microscope in good working order and whose lenses are clean. Set the low power objective (100X) in position. The light source should be a lamp. Plug in the scope and make certain the cord in not in the student work area. A spare microscope should be available in case of a malfunction.

  3. Arrange the materials at the student work station as indicated by the drawing below. Materials should be arranged the same for each student to be tested.

  4. Pieces of onion should be cut just prior to testing. Cut pieces approximately 1.25 cm x 1.25 cm. Be certain each piece has its epidermis. At least 4 pieces should be placed in a small dish for each student tested. New onion pieces are required for each student.

  5. Clean glass slides and plastic cover slips are to be used. Place the cover slips on an index card to make them more visible. Label the card at the bottom - PLASTIC COVER SLIPS.

  6. Label the dropper bottle - WATER.

  7. The prepared slide of colored threads, and the prepared slide of the onion epidermis should be numbered in the lower right corner of the slide with a permanent marker to code them for scoring of the papers. See the illustration below.

  8. The prepared slides must be coded to identify the following for scoring:

  1. Which colored thread is on top of the others.

  2. The number of onion cells arranged lengthwise and widthwise that span the diameter of the field of view.

  3. Use the chart below to keep a record of the prepared slides used.

Colored Threads Slide Number
Color of Top Thread


Onion Epidermis Slide Number
Cells Across the Field of
View Diameter
_______________ _______________ _______________
_______________ _______________ _______________
_______________ _______________ _______________


Instrument Part and Use Review

The following microscope parts and their uses should be reviewed with the students to re-acquaint them with their function.

  • ocular/eyepiece
  • turret/nosepiece
  • low power objective lens - 100x and/or color band
  • high power objective lens - 400/430x and/or color band
  • coarse adjustment
  • fine adjustment
  • stage and stage clips
  • diaphragm and its control
  • light source and its switch

Focusing Procedure Review

The basic technique for focusing a specimen under both low and high power should be briefly reviewed to prevent possible damage to the microscope. Remind students that only the fine adjustment should be used on high power to sharpen the image.


  • 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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