May/June 2017 – Vol. 29 No. 7

The “e” Alternative

Posted: Friday, October 1st, 2010

by Rick Pomeroy

This is a simple scenario-type lab that addresses the same concepts and processes that the traditional “e” microscope lab addresses but in a way that engages students in using evidence to solve a simple problem.  (A copy of the traditional lab is included at the bottom for your comparison.)  This activity is appropriate for grades 7-10, but can be adapted to any grade.  Providing the students with a purpose for looking at the print and writing samples under the microscope promotes critical thinking and demonstrates the ways that scientific tools can be used to answer real-world questions.  The level of description given by students of what they see when looking at the samples gives written context to the drawings that they are producing.  Emphasize that students should describe the texture of the paper as well as the way the “ink” is applied to the paper.  They will naturally draw the letters inverted, an observation which then allows further discussion of optics and magnification.

Preparation

  1. Create a ransom note about a scenario of your choosing and print it.
  2. Photocopy the note and then tear/shred the original into tiny pieces to give to the students.
  3. Obtain other samples of printing on different white papers with black ink, trying to make sure that the fonts are the same.  You might try printing the same passage on different papers on different printers or typewriters.  I suggest using the text from a newspaper or magazine article so that these paper and print types can be included as samples from suspects’ printers.  Suggestions for samples: ink jet printer, laser printer, typewriter, magazine article, newspaper article.  (The print and the paper quality will be different for each of these.)
  4. Place the samples from suspects’ printers in cups or dishes for students to access.
  5. Provide microscopes, slides, cover slips, etc. for students to use in their investigation.  (Compound microscopes on low power work great for this activity.)

Note: To prevent students from comparing answers, the teacher could provide several different ransom notes either within one period or for different periods.

Directions

  1. Read or relate the scenario description to the students.
  2. Provide samples of the note and samples from different printers on different types of paper.
  3. Instruct students that their task is to look at samples from the ransom note under the microscope and compare those samples with similar samples from the known sources of printer and paper evidence.
  4. Students should make a drawing of their sample from the ransom note and samples from the other printers.  The drawings should be detailed and accurate enough to support their conclusion as to what printer or what type of paper was used to create the ransom note.
  5. Students should write a brief statement describing which printer or what type of paper was used to create the ransom note and give evidence that supports their conclusion.  Part of their evidence should be their drawings.  Other evidence could be students’ statements about the type or quality of the paper as seen under the microscope.

The Scenario

This morning I received the following message in my mailbox.  I copied the letter to show to the principal and then, by mistake, I shredded the original.  Since I had just purchased a new shredder, I am sure that the samples that I have here are all from the ransom note.  Because of the content of the ransom note, I have also obtained printing  samples from the students who were in class yesterday.  Those people include AC, DJ, KE, JH, GJ, and NL.  Your task is to compare samples of the ransom note with the printing samples, make accurate drawings of what you see, and write a brief explanation of who you feel has the missing coffee cup.  Since I am going to go to this person and ask for my coffee cup back, your explanation MUST be supported by evidence.  Please include all evidence and drawings that you use to make your decision in your explanation.

The Note

Dear Rick,

When I was in your class today, I saw your elegantly engraved coffee cup sitting on the table.  Last night after everyone was gone, I entered the room and found your cup.  I just wanted you to know that I am willing to return it to you for the princely sum of eleven dollars and eleven cents.  If you ever want to see that coffee cup again, I would expect you to place the eleven dollars and eleven cents in an envelope and ease it under the front right corner of the candy machine down the hall.  No harm will come to the cup if you comply with this request.

Signed,  Me

The “e” lab (For comparison purposes only)

Purpose

The purpose of this lab is to learn about microscopes, how they invert images, and the differences in size of samples under 10x, 40x, and 100x magnification.

Materials

Obtain the following materials from your teacher:

  • Microscope with auxillary light source
  • Microscope slide and cover slip
  • Eye dropper and beaker of water
  • “e” sample from teacher

Procedure

  1. Set up your microscope as instructed by your teacher.
  2. Prepare a wet mount slide of the “e” by placing a drop of water on the center of your slide.
  3. Place the cover slip gently over the “e.”
  4. Look at the “e” under low power, medium power, and high power.
  5. Draw what you see in the appropriate circle below.



circlecircle

10x                                                   40x                                                 100x

Questions

  1. Describe in your own words the orientation of the “e” under the microscope.
  2. Describe in your own words how the sizes of the three views compared.
  3. Did the “e” look like you expected?

Rick Pomeroy is a teacher educator at the University of California, Davis, and is president-elect of CSTA. He can be reached at jrpomeroy@ucdavis.edu.

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Written by Rick Pomeroy

Rick Pomeroy

Rick Pomeroy is science education lecturer/supervisor in the School of Education, University of California Davis and is a past-president of CSTA.

2 Responses

  1. Hi Rick
    I really like the idea of promoting critical thinking & solving a “crime” in a simple lab, such as the “e lab.” I’m sure the students will really enjoy thing. Thanks for sharing.

  2. It sounds like fun I was looking for a microscope lab for my seventh grade class, i’ll copy this and see how it works.

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