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Counting Keratinocytes

Measuring Length in the Metric System


Jun Liang
Science Department
Borough of Manhattan Community College / City University of New York


This case study was developed for teaching metric length measurement in a non-majors biology laboratory setting. The case is suitable for lower-level non-major undergraduate or upper-level high school students. The case develops comprehension of the metric system, unit conversion, proper length measurement, precision, proportion, sample size, and determination of actual cell size from a histology image. Facility with these fundamental concepts and skills generally enhances the understanding of science. The case consists of three sections. Starting with an introduction to the metric system, students then move on to solve unit conversion questions and proportion problems. These activities build the foundation for the last part in which students determine actual cell size from a human skin tissue image. Students should complete the case in a sequential order, as complexity increases incrementally. The case engages students by having them measure their own height with a metric ruler and on that basis determine the number of cells needed to extend from “head to toe.”

  • Review the meaning of prefixes used to indicate length measurements in the metric system.
  • Practice unit conversion.
  • Measure the length of an object with a metric ruler.
  • Understand the terms proportion, ratio, and linear equation.
  • Understand how to use the scale bar in a microscopic histology tissue image.
  • Determine actual cell length from a histology image.
Keywords: Metric system; length measurement; cell size; unit conversion; proportion; ratio; customary; imperial
Topical Area: N/A
Educational Level: High school, Undergraduate lower division
Formats: PDF
Type/Method: Directed, Discussion
Language: English
Subject Headings: Biology (General)   Science (General)  
Date Posted: 4/22/2019
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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