Conservation of Mass Gum Lab

Nichol Reilly, Lake Nokomis Community School, Minneapolis, MN
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In this physical science lab, students investigate whether or not chewing gum should be considered eating. Students plan their own experiments for this lab. They use the law of conservation of mass to reason that the portion lost of the original mass of gum must be swallowed. Students determine the portion of original mass of gum that is swallowed for sugar and sugar-free gum. Students compare the two types of gum to make a claim about solubility. Students present their findings according to class norms (poster, written lab report, etc.)

Learning Goals

1. Students will develop and conduct an experiment to determine whether or not gum is a food.
2. Students will use the law of conservation of mass to determine the mass of gum swallowed during chewing.
3. Students will use graphs to illustrate mass swallowed over time.
4. Students will compare mass swallowed of sugar and sugar-free gum.
5. Students will use evidence to make a claim about the solubility of sugar vs. a sugar substitute.

Context for Use

This activity could be used at the beginning of the year to review conservation of mass and to reinforce lab safety (no gum in lab) or during a unit introducing the law of conservation of mass.

Description and Teaching Materials

Equipment: balance, sugar gum, sugar-free gum, calculator, graph paper or graphing software program
1. The teacher will review the rules of the laboratory with regard to eating. The teacher will raise the issue of gum. The teacher will lead the class to agree upon a definition of eating (Eating is having swallowed more than half the original mass.).
2. Students will work in lab groups to plan an experiment to determine whether or not chewing gum is eating according to the class definition of eating.
3. Students will have their plan approved by the teacher before proceeding with the experiment.
4. Students will work in lab groups to conduct their planned and approved experiments.
5. Students will write up and/or present their findings in a manner that is the class norm (written lab report, poster, etc.).

Teaching Notes and Tips

I have done this lab as a step-by-step lab. This is an adaptation allowing for a greater degree of inquiry, but I have not yet used it as such.


Lab notebooks and lab reports would be appropriate means of assessment.


The student will specify variables to be changed, controlled and measured. (IB1, grade 8)
The student will use appropriate technology and mathematics skills to access, gather, store, retrieve and organize data. (IB3, grade 8)
The student will design and complete a scientific experiment using scientific methods by determining a testable question, making a hypothesis, designing a scientific investigation with appropriate controls, analyzing data, making conclusions based on evidence and comparing conclusions to the original hypothesis and prior knowledge. (IB1, grade 9-12)
The student will explain how the rearrangement of atoms and molecules in a chemical reaction illustrates conservation of mass. (IIB4, grade 9-12)

References and Resources