Comparing Sizes of Microorganisms

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In this activity related to microbes, learners create scale models of microorganisms and compare relative sizes of common bacteria, viruses, fungi and protozoa using metric measures: meters, centimeters and micrometers. Learners will discover that microbes come in many different sizes and shapes, and frequently are measured in micrometers. This lesson guide includes background information and handouts.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
45 to 60 minutes

Estimated Materials Cost:
1 cent - $1 per group of students

Age Range:
Ages 8 - 14

Resource Types:
Activity, Lesson/Lesson Plan, Model


Materials List (per group of students)

  • Paper square (2.5 m x 2.5 m)
  • Set of 4 prepared text strips
  • 4 hand lenses (magnifiers)
  • 4 metric rulers marked in millimeters
  • 4 pairs of scissors
  • Assorted markers or colored pencils
  • Meter stick
  • Paper or science notebook
  • Several sheets of colored or plain paper, or roll of chart or kraft paper
  • Tape or glue
  • Copy of the Microbe Scaling Chart student sheet
  • Group concept map (ongoing, if available)


  • Engineering and Technology
    • Technology
      • Medical Technology
  • Life Sciences
    • Diversity of Life
      • Viruses and Bacteria
      • Protists and Fungi
      • Classification
    • Ecology
      • Biodiversity
  • Mathematics
    • Data Analysis and Probability
      • Data Analysis
    • Measurement
      • Units of Measurement
      • Size and Scale
      • Circles
    • Representation
  • Physical Sciences
    • Vibration and Waves
      • Light and Optics
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Informal Categories

  • Arts and Crafts
  • Model Building


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves teamwork and communication skills
  • Involves hands-on or lab activities


Components that are part of this resource:

Includes alignment to state and/or national standards:

Includes assesments for student learning:

This resource is part of:

Access Rights:

  • Free access


  • Moreno, Nancy P. ; Tharp, Barbara Z. ; Erdmann, Deanne B. ; Clayton, Sonia Rahmati ; Denk, James P.


  • All rights reserved, Baylor College of Medicine, 2008

Funding Source:

  • Science Education Partnership Award, 5R25 RR018605