SugarByHalf - Where's the Acid?

SugarByHalf - Where's the Acid?

Lesson 2 of 4 in this unit

  • Secondary
  • Year 9 - 10
  • Science
  • Biology
  • Chemistry
  • Social
  • Mental Health
  • Physical Health
  • ...

Lesson summary

In this lesson, students learn about how sugar causes tooth decay, and then carry out an experiment to independently verify that information.

Students start with the information that while sugar does cause tooth decay, it’s the bacteria in our mouths that turns the sugar into acid, rather than because the sugar is directly acidic. Students then test that information with an experiment to check the pH of sugar in solution.

As in the other lessons in this unit, the lesson ends with an opportunity for students to reflect on their learning; this learning in turn will feed into the science communication in the fourth lesson in this unit, Communicating the Science of Tooth Decay.

Learning intentions:

Students understand...

  • how to use a pH scale to check the acidity and alkalinity of a substance
  • how sugar relates to tooth decay
  • how to independently verify a scientific claim, and why that process is important

Success criteria:

Students can...

  • use indicators to test the pH of various substances
  • use experimental design to test a hypothesis
  • write a conclusion based on an experimental outcome
  • reflect critically on the practice of teaching and learning.

Lesson guides and printables

Lesson Plan
Teacher Content Info

Lesson details

Curriculum mapping

  • This lesson is part of the wider unit of work SugarByHalf – Science – Years 9-10
  • Time required: 60 mins
  • Level of teacher scaffolding: Medium – Facilitate class discussions, supervise experiments

To view our Australian Curriculum alignment click here

To view our NZ Curriculum alignment click here

Resources required

  • Bicarbonate soda or equivalent solution with a pH = 7.5
  • Cola
  • Data projector
  • Lactic acid solution or equivalent solution with a pH between 3.0 – 3.5
  • Litmus paper or universal indicator
  • Sugar and Dental Health factsheet
  • Sugar solution
  • Water

Additional info

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

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, heart disease, tooth decay, dementia and mental health conditions. A poor diet also puts children behind their peers, affecting brain development, sleep and ability to learn. Poor diet choices ultimately mean that this generation of children could be the first in modern history to live shorter lives than their parents.

Much of the added sugar in our diet comes from the processed foods and drinks we consume. On average, we consume 14-16 teaspoons of added sugar per day. Teenagers consume more than 20 teaspoons per day. The World Health Organisation says we should limit our daily added sugar intake to 6 teaspoons for good health. To put that in perspective, there are 4 grams of sugar in one teaspoon. If something has 20 grams of sugar, that's 5 teaspoons of sugar. 

This English lesson focuses on developing the skills and knowledge students need to critically consider messages about food and drink they are exposed to, thereby equipping them to be able to make healthy choices.

Talking about health

  • Be mindful of students who may experience weight stigma. Some students may be sensitive to conversations around weight, body size or shape. Terms including obesity, weight issues, weight-problem and fat can be stigmatising for some people because they assign blame. It is important to note individual preferences around language vary. Research has shown using the terms ‘weight’, ‘weight gain’, ‘healthy weight’, ‘unhealthy weight’, and ‘high BMI’ are preferred as better alternatives.
  • Be mindful about how you use the word ‘diet’. We recommend focussing students on the positive impacts of healthy nutrition and healthy lifestyles which help us to have stronger bodies and minds, feel good and sleep well.
  • Steer students away from any focus on appearances by communicating that appearance does not determine your worth. We recommend the fact sheets from the Butterfly Foundation on body image tips.
  • Avoid using labels such as obese or diabetic. Refer to people living with diabetes, people living with cancer, people with high BMI etc.
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