Lesson: How Much Sugar Is in Bubble Gum?

Summary

Some of the flavoring in bubble gum is due to the sugar or other sweetener it contains. As gum is chewed, the sugar dissolves and is swallowed. After a piece of gum loses its sweetness, it can be left to dry at room temperature and then the difference between its initial (unchewed) mass and its chewed mass can be used to calculate the percentage of sugar in the gum. This demonstration experiment is used to generate new questions about gums and their ingredients, and students can then design and execute new experiments based on their own questions.

Engineering Connection

When students design experiments to test their hypotheses, they are acting like scientists and engineers who are researching and devising new creations, everything from new devices to new cleaning products. Scientists practice engineering whenever they design new experiments to test hypotheses. Chemical engineers design and test all sorts of products in laboratories, everything from bubble gum to cough syrup to medicines to shampoo.

Educational Standards

•   Common Core State Standards for Mathematics: Math
•   International Technology and Engineering Educators Association: Technology
•   Next Generation Science Standards: Science
•   North Carolina: Math

Learning Objectives

After this lesson, students should be able to:
• Describe why a control is important in a scientific experiment.
• Distinguish between variables and controls in a scientific experiment.
• Describe an experiment to determine whether sugarless gum loses as much mass after chewing as regular gum does.

Introduction/Motivation

(Note to teacher: In most school curricula, students are asked to learn a lot about science, but rarely given the opportunity to do science. While they may learn a lot of content, they are seldom asked to generate their own questions about phenomena they observe around them, much less conduct controlled experiments aimed at answering those questions. However, in order to understand what the process of science is (and is not), it is important for students to be given opportunities to do the work of scientists.)
(Additionally, students are also rarely given the opportunity to chew gum in the classroom. However, the combination of hands-on activity and junk food is nearly irresistible to middle school students. Bubble gum, which is considered an illicit item in most schools, is an especially attractive material that can be used to teach the scientific method within the classroom.)
(Introduce the lesson by asking the class a few questions.) How long does the flavor last in your chewing gum? Have you ever wonder why gum loses its sweetness so quickly? Why is that? Does it seem like the gum gets smaller after you chew it? (Listen to a few ideas from students.) I would like you to do an experiment to test a hypothesis I have. This is my hypothesis: Sugar contributes to gum's flavor, and during chewing, the sugar is lost, which makes the gum get smaller as it loses its sweetness.
I will provide you with bubble gum and you will conduct the experiment. Are you ready? (Proceed to conduct the experiment, as described in the first part of the associated activity, Does Your Chewing Gum Lose Its Flavor?)

Lesson Background and Concepts for Teachers

A quick read of the nutrition label on a typical pack of bubble gum shows that one piece has a mass of about 8 grams, and of that mass, about 6 grams is sugar. Sugar dissolves readily in water, and about equally well in saliva. Some of the flavor in gum is due to the sugar, which dissolves in saliva and is swallowed, never to be tasted again. Also, the size of a wad of gum decreases considerably in the first 10 or 15 minutes of chewing. This change in volume is due to that same loss of sugar.
In the case of sugarless gum, the sweetener is typically a synthetic compound known as sorbitol, which may be listed as "sugar alcohol" on the nutrition label. It occurs in about the same proportion as sugar in regular gum, and it also dissolves in saliva, reducing both volume and sweetness, just as the sugar in regular gum does.
Realize that although technically sweetness is considered a "flavor" quality, almost all of the taste of foods (including gum) comes from their smells and hence, aromas. In fact, "80-90% of what we call flavor is olfactory, or smell-based." (Mary Roach, Gulp) Two pieces of gum, each with the same amount of sugar can taste dramatically different because of their different aromas. If your nose is congested so you cannot smell, you can observe sweet, salt, bitter, etc., tastes, but no aromas and hence, little real flavor. Challenge students to consider whether sugar and flavor are the same thing and what it is they are actually measuring in the associated activity experiment.

Associated Activities

• Does Your Chewing Gum Lose Its Sweetness? - Students conduct a teacher-initiated experiment to determine the amount of sugar in bubble gum, and then, based on questions that arise from it, design and conduct additional experiments to answer their own questions about the nature of gum.

Lesson Closure

After students have completed their experiments (in the associated activity), have them analyze their data by determining the amounts of mass lost from their gum and determining the percent of mass lost. Help them understand the percent of mass lost is the more important number, since the initial weights of the gum may not have been identical. Thus, if a larger piece of gum lost more mass than a smaller one, both may have had the same proportion of sugar all along. Only by calculating the percent of mass lost can we determine the relative proportions of sugar in different types of gum.
Next, have students prepare graphs of their results. Weights of gum before and after chewing can be shown in a bar graph, and the percentages of sugar in different types of gum can also be compared in bar graphs. If students conducted an experiment to see how the mass changes depending on how long the gum is chewed, they can show their results in an x-y scatter plot, with mass (the dependent variable, since it depends on how long the gum was chewed) on the y-axis and time (the independent variable) on the x-axis.
Then have each group share its findings with the rest of the class. A good way to do this is for each group to prepare a poster. Scientists and engineers frequently use posters as an efficient and timely means of communicating with each other when they get together at meetings devoted to a particular topic. Their posters contain the same types of information that would be covered in a formal paper published in a scientific journal:
• descriptive title
• description of the methods used to conduct the experiment, including diagrams, as appropriate
• results of the experiment, shown in tables and graphs, and summarized in words
• conclusions drawn from the data
Give students a day or two of class time to prepare a "semi-formal" poster to display in the classroom. Expect the posters to be formal in the sense that they give sufficient and objective reportings of the experiments, are neat, and use correct grammar and spelling. However, encourage students to express their creativity in the way they lay out and embellish their posters with color, graphics, font sizes, illustrations, etc., so they are successful in communicating to readers.
Because good poster preparation requires many components, all students have opportunities to contribute in ways that highlight their own particular strengths. When posters are done, have group present them to the rest of the class along with brief summaries of the results and conclusions. Encourage other students to ask questions and give feedback to the presenting group.

Assessment

Poster Presentations: Have teams graph and analyze their experimental data, and present their results and conclusions in poster format to share with the rest of the class, as described in the Lesson Closure section. Review their posters to gauge their comprehension of the subject matter and concepts.
Written Wrap-Up: As a concluding assignment, ask students to write answers to the following questions:
• Explain why a control should have been used in the initial gum experiment.
• Describe an experiment to determine whether sugarless gum loses as much mass after chewing as regular gum does.

Lesson Extension Activities

Assign students to conduct Internet or library research to discover some interesting history and facts about chewing gum, including how it is made by chemical engineers. For example, did you know that it is impossible to make chocolate gum?
Use this lesson as part of a unit on chemistry; it makes a good way to introduce the biochemically important sugars.

Contributors

Mary R. Hebrank, project writer and consultant, Duke University

© 2013 by Regents of the University of Colorado; original © 2004 Duke University

Supporting Program

Engineering K-PhD Program, Pratt School of Engineering, Duke University

Acknowledgements

This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.
This lesson and its associated activity were originally published, in slightly modified form, by Duke University's Center for Inquiry Based Learning (CIBL). Please visit http://www.ciblearning.org/ for information about CIBL and other resources for K-12 science and math teachers.
The basic idea and method of this lesson and activity, although much modified here, originated in an article by high school teacher Louis Gotlib that was published in a newsletter of the North Carolina Science Teachers Association. "Finding the Percentage of Sugar in Gum" first appeared in NCSTA Teaching Notes #5, 1997.