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LESSON PLAN in Acid Base Reactions, Percent Composition, Le Châtelier's Principle, Equilibrium, Predicting Products, Reactions & Stoichiometry, Acids & Bases, ACS National Historic Chemical Landmarks Program. Last updated April 29, 2026.

Summary

In this lesson, students will learn about the development of Crest fluoridated toothpaste by reading an article and engaging in related activities. The activities help promote literacy in the science classroom. Parts of this lesson could be used as plans for a substitute teacher.

Grade Level

High School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
  • HS-PS1-6: Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.
  • HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
  • Scientific and Engineering Practices:
    • Planning and Carrying Out Investigations
    • Constructing Explanations and Designing Solutions
    • Engaging in Argument from Evidence
    • Obtaining, Evaluating, and Communicating Information

Objectives

By the end of this lesson, students should be able to:

  • Provide an overview of the development of fluoridated toothpaste and explain the challenges that had to be overcome.
  • List the common ingredients in toothpaste and explain what each one does.
  • Explain the terms mineralization and demineralization in terms of tooth enamel.
  • Name the various parts of a tooth and note which part(s) are significant in terms of protection from cavities.
  • Understand and provide examples of the role of saliva in oral health.
  • Explain the meaning of biofilm, and why it is of concern in maintaining good oral hygiene.
  • Provide examples of arguments for and against the fluoridation of public drinking water.
  • Ask questions about claims made by different information sources and be able to ask questions about data presented.

Chemistry Topics

This lesson supports students’ understanding of:

  • Equilibrium
  • Le Châtelier’s Principle
  • Acid-base Reactions
  • Predicting Products
  • Percent Composition
  • Stoichiometry
  • Concentration

Time

Teacher Preparation:

  • 15 - 20 minutes to make copies of materials
  • 5 minutes for the Demineralization Lab setup.

Lesson: Approximate times for students to complete each activity in the lesson:

  • Anticipation Guide: 10 minutes
  • Reading: 20 minutes
  • Toothpaste Video Shorts: 20 minutes
  • Teeth, Saliva and Biofilm: 35-45 minutes
  • Quantitative Dentistry: 60 minutes
  • Toothpaste Chemistry: 30-40 minutes
  • Demineralization Lab: 45-60 minutes (Day 1: 15 minutes; Day 3: 30-45minutes)
  • The Great Fluoride Controversy: 60 minutes

Materials

  • Access to the internet
  • Demineralization lab (per student group):
    • 2 white eggs
    • 2 small beakers or small clear cups (large enough to hold an egg)
    • vinegar (enough to submerge each egg)

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.

Teacher Notes

Background:

Lesson Overview:

The lesson includes multiple components, as outlined individually below. The Reading is essential for all of the activities. Teachers can choose to do one or all of the included activities. Student handouts and corresponding answer keys are provided for each item described below:

  • Activity: Anticipation Guide
  • Reading: Crest Toothpaste
    • Students identify whether they agree or disagree with the ten statements. After they complete the reading, they can adjust their answers and rephrase “disagree” statements, so they read true.
  • Activity: Teeth, Saliva, and Biofilm
    • Students learn a little more about what is happening in their mouths by examining images provided in the activity and answering questions about them. They will learn about tooth structure and function, the role of saliva in oral health, and finally what biofilm is, and why it is important.
  • Activity: Quantitative Dentistry
    • This activity provides students with the opportunity to practice chemistry calculations through the dentistry lens. Questions related to the following topics are included: percent composition, determining empirical and molecular formulas, stoichiometry, equilibrium and concentration conversions.
  • Activity: Toothpaste Chemistry
    • This activity familiarizes students with the main ingredients in toothpaste, and the purpose of those ingredients. Students will complete a graphic organizer to summarize what they learn from links provided in the activity.
  • Activity: Demineralization Lab
    • This is a simple lab used to demonstrate the effect of acid on eggshells, specifically the process of demineralization. Students can consider the results of this lab experience and apply it to the demineralization process in teeth. In addition to observations, students will learn about the chemical reactions involved when eggshells and teeth are exposed to fluoride and to acid.
  • Activity: The Great Fluoride Controversy
    • This activity is designed to help students develop critical thinking skills, specifically how to respond to a claim that begins with “studies show…”. By examining a series of online infographics and watching an ACS Reactions video, students will learn about the kinds of questions they need to ask when evaluating a claim.

  • Related classroom resources from the AACT library and ACS that may be used to further teach this topic:
  • Infographics:
  • Additional background information: