Chemical Methods of Control

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In this lab, learners evaluate the relative effectiveness of various chemical substances (i.e. garlic powder, bathroom cleaner, mouthwash, etc.) as antimicrobial agents. Learners use the agar diffusion method to determine "zones of inhibition." This lesson guide includes background information, questions for learners, and additional activity ideas.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
4 to 24 hours

Estimated Materials Cost:
$5 - $10 per student

Age Range:
Ages 11 - 18

Resource Types:
Activity, Experiment/Lab Activity, Lesson/Lesson Plan


Materials List (per student)

  • Petri plates containing nutrient agar (2)
  • Sterile cotton swab
  • Forceps
  • Ruler
  • Disks (use a hole punch on filter paper)
  • Test substances: Garlic powder, chemical agents such as bathroom cleaner, floor cleaner, mouthwash, lens cleaner, acne cleaner. Bring your own.
  • Staphylococcus epidermis (Gram-positive)
  • Escherichia coli (Gram-negative)


  • Life Sciences
    • Cells
    • Diversity of Life
      • Viruses and Bacteria
    • Human Body
      • Health and Nutrition
  • Physical Sciences
    • Chemistry
  • Mathematics
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Uses STEM to solve real-world problems
  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access


  • Slowiczek, Ed.D., Fran ; Peters, Ph.D., Pamela M.