Activity Introduction

This lesson introduces the idea of acids and bases, using the context and framing of tooth decay. It offers a fun new hook into a very familiar, traditional part of the curriculum.

Students will come to understand how acids and bases work, but also learn about how it relates to the science of cavities, giving that knowledge an immediate and personal relevance in their everyday lives. The lesson ends with an opportunity for students to reflect on their learning; this learning in turn feeds into the science communication in the final lesson in this unit, Communicating the Science of Tooth Decay.


Learning Intentions

  • Students understand and describe the properties of acids and bases
  • Students recognise the role hydrogen ions play in the acidic, neutral or alkaline properties of a substance
  • Students understand the pH scale and how to use it to determine a substance’s acidity or alkalinity
  • Students understand how tooth decay happens and what they can do to prevent or minimise it.

Lesson & Curriculum Details

  • Topic: Consumption. 
  • This lesson is part of the wider unit of work SugarByHalf – Science – Years 9-10
  • Time required: 55 mins.
  • Level of teacher scaffolding: Low – As an introduction to the sequence of lessons on this topic, there will be more explicit teaching of concepts required in order to bring students up to speed on the science behind pH before some of the application material is presented.
  • Keywords: acid, base, alkaline, pH, ion, hydrogen, electron, proton, teeth, tooth decay, cavities, Australian Dental Association, SugarByHalf.

To view our Australian Curriculum alignment click here.

To view our NZ Curriculum alignment click here.

Cool Australia’s curriculum team continually reviews and refines our resources to be in line with changes to the Australian and New Zealand Curriculums.

Resources Required

  • Data projector
  • pH chart


These lessons were developed in partnership with SugarByHalf and the Australian Dental Association.


Teacher Worksheet

Teacher Preparation

Learning intentions: Students understand...

  • … how to describe properties of acids and bases
    … the role hydrogen ions play in the acidic, neutral or alkaline properties of a substance
    … the pH scale and how to use it to determine a substance's acidity or alkalinity
    … how tooth decay occurs and what can be done to prevent or minimise it.

Success criteria: Students can...

  • … identify the properties that make up an acid and a base
    … label all of the features of a pH scale
    … use a pH scale to help identify the strength of acids and bases
    … reflect critically on the practice of teaching and learning.

Teacher content information:

SugarByHalf ( promotes action to reduce sugar-related diseases so that we can live better, stronger and healthier lives.

Their message is simple: to reduce added sugar consumption by half. Eating too much added sugar is a key driver of serious health problems including obesity, type 2 diabetes,

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