Sink or Float – Exploring Density
Indiana Expeditions Show
Physical Science
Overview
Given a variety of twelve-ounce unopened cans of regular and diet soda, students will
predict and then test whether they will sink or float in water.
Background Information
Density, the ratio of the amount of matter (mass) in an object compared to its volume (the
amount of space it takes up), is a physical property of all matter. If two objects have the
same volume but one has more mass, then the object with more mass has a greater
density. For example, two spheres of the same exact size but with different masses will
have the same volume but, because their mass is different, they will have different
densities.
Each of the twelve-ounce unopened cans of soda take up the same amount of space.
Thus, they have the same volume. So, what is the difference between a can of diet soda
and a can of regular soda? The type of sweetener used! Regular soda is sweetened with
sugar. Most of the time, there is a great deal of sugar dissolved in a regular can of soda.
Check the ingredients label on a can of regular soda to discover just how much sugar is in
one can! The diet soda is sweetened using an artificial sweetener. Artificial sweeteners
are much sweeter than sugar and thus, less artificial sweetener is needed to make a diet
soda taste sweet. So, the can of diet soda, while it has the same volume as a can of
regular soda, has less mass. Placing a can of regular soda and a can of diet soda on a
balance should confirm that although they may look alike, they have different masses and
thus, different densities.
Connections to the Indiana Academic Standards for Science
3.1.2, 3.1.3, 3.1.4, 3.1.5, 3.2.4, 3.2.6, 3.4.5, 4.1.3, 4.2.5, 5.1.3, 5.1.4, 5.4.8, 5.5.6,
6.1.4, 6.1.5, 6.2.7, 6.2.8, 7.1.4
Science Process Skills
 Communicating
 Classifying
 Hypothesizing
 Inferring
 Measuring
 Observing
Estimated Time Requirement
One 45-minute session
Materials
 One empty two-liter plastic bottle for each group of three students.
 One 12-ounce can of regular soda*
 One 12-ounce can of the diet soda*
 Paper towels
 Water source
 One “Sink or Float” lab handout for each student
 Two plastic eggs (Be sure the eggs are the same size and color! Note: Any small
opaque containers that are the same size will work. For example, two empty
film canisters may be used.)
 Tape
 Sand
 Measuring tools: rulers, tape measures, balances
*the regular and diet soda should be the same brand
Objectives
Students will be able to
1. Formulate and test a hypothesis.
2. Differentiate between volume and mass.
3. Explain that objects with similar volumes but different masses will have
different densities.
Procedure
Preparation prior to the lesson:
 Cut off the tops of the two-liter bottles to make water tanks for the sink or float
experiment.
 Tape one of the plastic eggs shut. Completely fill the other plastic egg with sand
and then tape it shut.
Anticipatory set:
 Show the students the two plastic eggs but do not let them handle the eggs. Ask
them for observations. (How are the eggs similar? How are they different?)
Ask them what they think will happen if you place the eggs in a container of
water – will they sink or float? Ask students to provide some explanations for
their answers. Place the two eggs in the water. One will float and the other will
sink. Ask students why this happened. Tell them they will be conducting an
experiment to determine why objects sink or float.
Lesson sequence:
 Introduce the concept of density as a ratio of mass in an object compared to its
volume by drawing these cubes on the board.
 Ask the students to compare the volumes of the two cubes and then to compare
the masses of the two cubes. Elicit from students that the masses of the cubes
differ, thus the cubes have different densities. Ask them to explain which cube
has a greater density and why.
 Help students understand that both containers from the anticipatory set activity
have the same volume so in order to have different densities, they must have
different masses.
 Divide the class into groups of three and distribute this equipment to each group:
one “Sink or Float” lab handout per student, one 12-ounce can of regular soda,
one 12-ounce can of diet soda, one empty water tank, and paper towels.
 Direct students to develop an investigation question about the cans of soda based
upon what they observed with the eggs.
 Have students draw and write observations on their lab sheet about each can of
soda. Point out the measuring tools that are available and encourage them to use
the tools as they make their observations.
 After students have made their observations, instruct them to develop a
hypothesis about which can of soda has a greater density and to predict whether
each can will float or sink.
 Once students have developed a hypothesis allow them to fill their water tanks
with enough water so it would cover the can if the can was placed in the
container.
 Instruct students to conduct the multiple trials of the experiment and record
their data in the table provided on the lab sheet.
 When finished, students should clean up their materials and then write a
conclusion to complete their lab sheet.
Closure:
 Revisit the eggs and ask students what they think happened. Then, allow the
students to handle the eggs to confirm or refute their ideas.
 View the Physical Science Indiana Expeditions segment.
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Suggested Student Assessment
Objective #1:
Collect and assess the completed “Sink or Float” lab handouts.
Objective #2:
Provide students with a variety of objects and ask them to determine their volume
and their mass.
Objective #3:
Use the “Density Diagrams Assessment” and written or verbal responses from
students to assess their understanding of the relationship between volume, mass,
and density.
Extending the Lesson
 Challenge students to find common objects that will float in water and common
objects that will sink in water.
 Provide students with the same-sized cubes of different substances (for example,
a wood block, a metal block, a block of clay, and a block of butter) and ask them
to predict which ones will float and which ones will sink. Try it!
 Show students a real egg and a container of water. Ask them what they think
will happen if you place the egg in the water – will it sink or float? Try it.
Explain to students that water, in its liquid form, has a specific density. Because
it sank, the egg has a greater density than the water. Challenge students to
explore what they can do to the water to increase its density so the egg will float.
(Hint: Ask students to remember the difference between the regular soda and the
diet soda. This should help them think about adding something to the water to
change its density.)
Source of Lesson
Rick Crosslin
Educator - M.S.D. Wayne Township
School Liaison for Science Learning - The Children's Museum of Indianapolis
The Children’s Museum of Indianapolis, ScienceWorks Unit of Study
http://www.childrensmuseum.org/teachers/unitsofstudy/scienceworks/index.htm
Deb Sachs
Director, Office of Professional Development
School of Education
University of Indianapolis
Sink or Float
Name________________________________________________________
My investigation question:
_____________________________________________________________
_____________________________________________________________
My observations: (Draw and write your observations.)
Regular Soda
Diet Soda
________________________
_______________________
________________________
_______________________
________________________
_______________________
________________________
_______________________
________________________
_______________________
________________________
_______________________
My hypothesis: (Write a sentence stating which can of soda you think has a
greater density.)
_____________________________________________________________
_____________________________________________________________
My prediction and data from my experiment:
Circle your predictions and record the results of your experiment below.
My
Type of prediction
Test One
Test Two
Test Three
Test Four
Soda
(circle
one)
Regular
Sink
Sink Float Sink Float Sink Float Sink Float
Soda
Float
Diet
Sink
Sink Float Sink Float Sink Float Sink Float
Soda
Float
My conclusion:
Interpret (explain) the results of your experiment and state your conclusion.
Be sure to include the following words in your explanation: dense or density,
data, regular soda, diet soda.
Density Diagrams Assessment
Name________________________________________________________
Use the illustration of the two cylinders below to describe the relationship
between volume, mass, and density. Be sure to include the following
words in your explanation: volume, mass, matter, density or dense.
Cylinder A
Cylinder B
1 liter container
1 liter container
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