Basic Concepts
Title: Grape Weight
Grade Level: 9-12
Subject/Content: Science, Earth and Space Science
Summary of Lesson: Students will observe how the density of a liquid changes as more
solute (sugar) is added to the solution. Students will do this by observing whether a grape
can float or sink when placed into different density sugar solutions.
Focus Question: What concentration of sugar solution will result in the densities of the
grape and solution being equal?
Resource: Science in Context
Procedures:
Steps/Activities by the Teacher:
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Perform a demonstration that asks students to determine if a certain object will
float or sink in a large beaker of water. Show a few examples of objects that
float and a few examples of objects that sink. Explain to students that this is
caused by the different densities of the different objects.
Lead a class discussion about density. Explain that density is the amount of
mass an object has divided by the object’s volume. Speak briefly about how
density works on a molecular level.
Direct students to research and take notes on the topic of density using Science
in Context as a resource.
Arrange students into groups of two.
Inform students that they will be doing an experiment to determine the density
of a grape. Have students write down the focus question at the top of their
paper, “What concentration of sugar solution will result in the densities of the
grape and solution being equal?”
Direct students to copy down the data table below:
Grams of Sugar per
100mL of solution
0
10
20
30
40
__
Did the grape float or
sink?
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Direct students to create solutions with the following amounts of sugar, in grams.
To create these solutions, students should add the sugar first and then fill up the
beaker to the 100mL mark. Students should then test a grape in each solution to
see if the grape sinks or floats.
For added complexity, direct students to find the molarity of sugar in each of
their solutions.
Direct students to create their own solution for the final test. Their solution
should attempt to find the concentration of sugar in the solution that will be
exactly the same density as the grape.
Direct students to answer the following questions with their partners:
1. Does increasing the concentration of sugar in the solution make the
solution more or less dense? Explain your answer using evidence from
your experiment.
2. Does increasing the concentration of sugar in the solution change the
density of the grape? Why or why not?
3. On a molecular level, why is the density of the solution changing as
more sugar is added? Explain using both writing and pictures.
4. Why did you choose your final concentration of sugar? Explain using
data from your experiment.
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Direct students to finish the experiment by finding the exact density of a grape.
Weighing the grape will provide the grape’s mass and submerging the grape
underwater in a graduated cylinder will provide the grape’s volume via the
displacement of water.
For added complexity, have the students who finish their questions first attempt
to figure out how to find the volume of a grape by themselves.
Steps/Activities by Student(s):
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Research and take notes about all relevant information pertaining to ‘density’
using Science in Context.
Get together with a partner and copy down the following data table onto your
paper.
Grams of Sugar per
100mL of solution
0
10
20
30
40
__

Did the grape float or
sink?
Create solutions with the amounts of sugar listed on your data table. To make
the solutions, first add the amount of sugar, in grams, to a beaker. Then fill the
beaker up with water to the 100mL mark.

Test the grape in each solution and record data on whether the grape sinks or
floats.

Create your own solution for the final test. Use the information that you have
collected so far to hypothesize about what exact concentration of sugar will result
in the solution and the grape having the same density.
Answer the following questions with your partner:

1. Does increasing the concentration of sugar in the solution make the
solution more or less dense? Explain your answer using evidence from
your experiment.
2. Does increasing the concentration of sugar in the solution change the
density of the grape? Why or why not?
3. On a molecular level, why is the density of the solution changing as
more sugar is added? Explain using both writing and pictures.
4. Why did you choose your final concentration of sugar? Explain using
data from your experiment.

Find the exact density of the grape. Weigh the grape to find the grape’s mass, in
grams, and submerge the grape underwater in a graduated cylinder to find the
grape’s volume by measuring the amount of water displaced, in milliliters.
Outcome: Students will gain a deeper understanding of the idea of density. Students will
be able to calculate the density of an object and make predictions about how densities
between two objects compare.
Related Activities:
Biology
 Research the ‘swim bladder’ using Science in Context as a resource. Lead a
class discussion about how fish use swim bladders to change their density so
that they can keep their density equal to that of the water around them. Build
a model that can represent a fish with a swim bladder and inflate it at different
amounts and observe what happens.
Learning Expectation: Students will use their research skills to find relevant information
about density. Students will use their analytical skills to make predictions and explanations
using data.
Standards Alignment
Next Generation Science Standards
HS-PS2.CC.4.1. Investigating or designing new systems or structures requires a detailed
examination of the properties of different materials, the structures of different components,
and connections of components to reveal its function and/or solve a problem. (HS-PS2-6)
Standard Source: Next Generation Science Standards (2013)
Common Core State Standards
Grades 9-10
CCSS.ELA-Literacy.RST.9-10.2
Determine the central ideas or conclusions of a text;
trace the text's explanation or depiction of a complex process, phenomenon, or concept;
provide an accurate summary of the text.
CCSS.ELA-Literacy.RST.9-10.3
Follow precisely a complex multistep procedure when
carrying out experiments, taking measurements, or performing technical tasks attending to
special cases or exceptions defined in the text.
CCSS.ELA-Literacy.RST.9-10.4
Determine the meaning of symbols, key terms, and
other domain-specific words and phrases as they are used in a specific scientific or technical
context relevant to grades 9-10 texts and topics.
CCSS.ELA-Literacy.RST.9-10.5
Analyze the structure of the relationships among
concepts in a text, including relationships among key terms (e.g., force, friction, reaction
force, energy).
CCSS.ELA-Literacy.RST.9-10.10
By the end of grade 10, read and comprehend
science/technical texts in the grades 9-10 text complexity band independently and
proficiently.
CCSS.ELA-Literacy.WHST.9-10.1
Write arguments focused on discipline-specific content.
Grades 11-12
CCSS.ELA-Literacy.RST.11-12.2
Determine the central ideas or conclusions of a text;
summarize complex concepts, processes, or information presented in a text by paraphrasing
them in simpler but still accurate terms.
CCSS.ELA-Literacy.RST.11-12.3
Follow precisely a complex multistep procedure when
carrying out experiments, taking measurements, or performing technical tasks; analyze the
specific results based on explanations in the text.
CCSS.ELA-Literacy.RST.11-12.4
Determine the meaning of symbols, key terms, and
other domain-specific words and phrases as they are used in a specific scientific or technical
context relevant to grades 11-12 texts and topics.
CCSS.ELA-Literacy.RST.11-12.10 By the end of grade 12, read and comprehend
science/technical texts in the grades 11-12 text complexity band independently and
proficiently.
CCSS.ELA-Literacy.WHST.11-12.4 Produce clear and coherent writing in which the
development, organization, and style are appropriate to task, purpose, and audience.
Standard Source: Common Core State Standards Initiative (2010)