Teacher Guide to a Model Experiment "Chewing Gum" (grade 8-9)

```Lab Activity for Grade 8 Research: What is the Effect of Chewing on the Change in Mass of Gum?
Teacher Notes:
This activity can be conducted in 4 periods.
This activity reinforces the concepts of the Scientific Method and Components of Experimental Design units, measuring
mass lab skills, data table construction, and design of independent research project ideas. It also includes graphing
(recommended to use Excel or Google equivalent (“Sheets”).
The best time to do this activity is after these units and the measuring mass lab skill is covered. Data table construction
can be taught after the day 1 data collection. Additionally, if time permits (ITP), graphing the results can de discussed.
Plan
Day 1: explain the experiment, identify all the components of experimental design, decide on a hypothesis (as a class)
review the procedure, start data table design.
Day 2: Day 1 of the experiment requires ~1/2 period. Continue data table design. Discuss graphing (ITP)
Day 3: Day 2 of the experiment requires &lt;1/2 period. Recommended option is to use Excel for graphing
Day 4: wrap-up, bar graph results, decide on a conclusion and propose other experiments
Possible IVs: type of gum (sugarless vs. sugared works well), amount of time chewed, combination of type of gum and
amount of time chewed (see exemplars).
Prep
Teacher(s) should purchase several multi-packs of a variety of sugared gums and one sugarless (i.e. Trident)
Helpful tip: I timed the chewing for the whole class to start and stop at the same time
Instructional Presentations (PPTs) available in Google Shared Drive  8th &amp; 9th Grade Resources
 Units 1, 2 &amp; 3
Scientific Method
Defining the Elements of Experimental Design
 More Unit 3 Resources
How to Use the Electric Scale
Guided Investigation Chewing Gum
Unguided Investigation Chewing Gum
How to Make Data Tables
How to Make Good Data Tables
Topic: Experimental Design
Experimental Design = how an experiment is set-up
The Parts of Experimental Design are:
PS = the Research Question or the Problem Statement
H = hypothesis
IV = manipulated (changed) by the experimenter
DV = what responds to the change on the IV
Assay = what is measured and how (measuring instrument)
Constants (controlled variables)
Topic: Data Tables for the Experiment-What is the Effect of Chewing on the Change in Mass of Gum?
All data tables must have:
A title. Capitalization Rule: First word, all words three letters of more, except
“and” and “the”
B. Grid lines
D. Units – ONLY in the title and the column/row headings, NOT in the cells.
E. Center justify all titles, headings and contents of all cells
Topic: The Experiment, Elements of Experimental Design-What is the Effect of Chewing on the Change in Mass of Gum?
What is the…? Effect of Chewing on the Change in Mass of Gum
IV = chewing
DV = change in mass of the gum
Constants = time of chewing
Assay = a) What is measured? – mass of gum BEFORE and AFTER chewing
b) How measured? – using an electric scale,
Hypothesis = IF the gum is chewed THEN mass will --Alternative IVs and Levels of IVs:
Different gums (sugarless vs sugared), Different times of chewing
What is the control for this (these) experiment(s)?
Answer: the mass of the gum before it is chewed
Topic: Protocols
Protocols are: how the experiment is conducted
Protocols include A. Materials List and B. A stepwise Methods List
Protocols are different from Experimental Design because:
It doesn’t define the variables (IV, DV, etc.)
The Protocol for the Experiment:
A. Materials
1. Gum
2. Electric Scale
3. Tare Boat
4. Timer
B. Methods Day 1
1. Obtain materials
2. Label the tare boat with your name
3. Zero electric scale
4. Mass the tare boat and record the mass in your lab notebook and on the
tare boat too
5. Zero electric scale and tare the tare boat
6. Add un-chewed gum to tare boat and record mass in your lab notebook. You
should now have the mass of the empty tare boat and the mass of the
unchewed gum recorded in your lab notebook.
6. When ready, use the timer to chew gum for 3 min.
7. When the time is up, remove and store in tare boat for 24 hours (overnight)
Day 2
7. Retrieve tare boat containing chewed gum from Day 1
8. Zero electric scale and mass tare boat containing gum and subtract mass of
tare boat (from Day 1) to get new mass of gum and record in your lab
notebook
Exemplars
A
Data Tables and Graphs for the Experiment (an example from actual experiment, IV = one brand, Winterfresh)
Title: What is the Effect of Chewing on the Change in Mass of Gum?
Set-up the grid, column/row headings with units
Trial #
Mass of Gum Before
Mass of Gum After
Change in Mass
Chewing
Chewing
(g)
(g)
(g)
1
2.9
1.1
-1.8
2
2.7
1.0
-1.7
3
2.7
1.1
-1.6
4
2.7
1.0
-1.7
AVERAGE
2.75
1.05
Brand = Winterfresh
Bar Graph
3
The Effect of Chewing on the Change in Mass of
Gum
2,5
Mass (g)
2
1,5
1
0,5
0
Before
After
Before and After Chewing
B
The Effect of Time of Chewing on the Change in Mass of Two Types of Gum; Sugared and Sugarless
Time of Chewing (min)
Change in Mass (g)
Change in Mass (g)
Of Sugared Gum
Of Sugarless Gum
Winter Fresh
Trident
0 (Control)
0
0
1
-0.9
-0.7
2
-0.9
-0.1
3
-0.1
-0.1
Percent Mass Lost
A Comparison of the Effect of Time
of Chewing on the Percent Change
in Mass of Two Different Types of
Gum; Sugared and Sugarless
80
70
60
50
40
30
20
10
Sugar
0
1
2
3
Time (min)
4
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