Density

4th Grade Science
Matter
Lesson 3

Teacher Facing
August 16, 2024

MRS Icons

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Emergent Bilingual Support

To support English learners in language
acquisition, consider using the following
resources:

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Thinking Stems

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Language Functions Tool

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Teacher Background

Background Knowledge for Teacher
Students have had multiple opportunities in previous years to observe objects that sink or float,
usually in water. For example, oil and water as found in Italian salad dressing demonstrates that oil
floats on top because it is less dense than the water (relative density). Give students opportunities to
further explore this comparison with a variety of items.

Density is defined as how much mass there is in a unit of volume. If two objects with the same volume
have different masses, the one with the greater mass has a higher density.

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Possible Student Misconceptions

●Small objects float, and large objects sink.

●Soft objects float, and hard objects sink.

●Floating objects have air in them somewhere.

4th Grade Science
Matter
Lesson 3

August 16, 2024

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Matter

LO: SWBAT classify and describe matter based on
relative density.

DOL: Given scenarios, SW correctly classify and
describe matter based on relative density in at least 4
of 5 questions.

SCI.4.6A Classify and describe matter using observable physical properties, including temperature, mass, magnetism, relative density
(the ability to sink or float in water), and physical state (solid, liquid, gas);
SEPs 5.1A
RTCs

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Essential Understandings &

Guiding Questions

How can we test an object’s ability to sink or float?

What materials are more or less dense than water?

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Lesson Vocabulary

Physical Property

Relative Density

Sink

Float

Poll

Why does a rick sink and a pillow float?

• Density

• Volume

Multiple Choice

What is MASS?

• how much space something takes up

• the amount of matter in something

• the height of something

• the color of an object

Multiple Choice

Which two measurements do you need in order to calculate the DENSITY of an object or substance?

• mass & volume

• height & weight

• color & size

• length & size

Multiple Choice

Which of these would have the greatest (most) VOLUME?

• an ant

• a pillow

• a pencil

• a paper clip

Multiple Choice

Why does a small rock sink in water?

• because it is more dense than the water

• because it is small

• because it doesn't weigh a lot

• because it is less dense than the water

Multiple Choice

What is the density of plain water?

• 100

• 17

• 144

• 1

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How can little
pebbles sink to the
bottom of a cup of
water but giant
things like boats
(and huge rubber
ducks) can float?

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What materials are more or less dense than
water?

1 Predict

Examine the objects
you are going to test.

Discuss your
predictions.

2 Investigate

Organize the materials
into two groups: small

objects and large

objects. Then follow the
steps to test the items.

3 Record

Use the table to

identify if the objects
float or sink in water.

4 Classify

Use your data to
classify objects

based on their ability

to sink or float.

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Make Meaning

DescribeHow can you determine if a material
has a higher or lower density than water?

If a material has a higher
density than water, it will sink.

If a material has a lower
density than water, it will float.

Copyright © Savvas Learning Company LLC. All Rights Reserved. Savvas is not responsible for any modifications made by end users to the content posted in its original format.

What is relative density?

Relative density is an object’s ability to sink or float in water.
Objects that are less dense than water will float. Objects that
are more dense than water will sink.

Copyright © Savvas Learning Company LLC. All Rights Reserved. Savvas is not responsible for any modifications made by end users to the content posted in its original format.

Relative Density

Classify How can you use what you have learned about relative
density to classify these objects?

Sample answer: The ball
at the bottom of the tank
is more dense than water.
The ball floating on the
surface of the water is
less dense than water.

Photo credit: Alexandre Dotta/Science Source

Copyright © Savvas Learning Company LLC. All Rights Reserved. Savvas is not responsible for any modifications made by end users to the content posted in its original format.

Sink or Float

Do larger objects sink and smaller objects float?

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How can little
pebbles sink to the
bottom of a cup of
water but giant
things like boats
(and huge rubber
ducks) can float?

Let’s Revisit the Phenomena

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Relative Density

The ability of a
substance to sink
or float when
placed in water

© Ihor95 – stock.adobe.com

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A student conducted a sink or float lab and recorded their
observations in the table below.

Explain why the toothpick floated in water and the rock and
nail sink in water.

Object

It Floats

It Sinks

Rock

X

Toothpick

X

Nail

X

Sink or Float

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A student places a small cube of wood into a beaker filled
with water. The wood floats on top of the water. Which of
these bests explains why the wood block floats?

A.

Most objects will float on water.

B.

The wood cube is less dense than the water.

C.

The wood cube has less mass than the water.

D.

The water has more volume than the wood cube.

Relative Density

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DOL: Given
scenarios, SW
correctly classify and
describe matter
based on relative
density in at least 4
of 5 questions.

Demonstration of Learning

●Some images used in this lesson are taken from Adobe Stock. Adobe Stock
https://stock.adobe.com

●Some images used in this lesson are taken from Great Minds. Great Minds
https://digital.greatminds.org

●Some images used in this lesson are taken from SAVVAS realize. SAVVAS
realize https://www.savvasrealize.com

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Copyright for Reference