Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 18762
Density – a relationship of mass and volume
Students will be able to describe density and compare the densities of various materials using their masses and volumes.
Content statements:
Density is the amount of matter filling the object's space.
Adding mass to an object without changing its volume, increases the object's density.
Objects that have a large mass and small volume have a high density.
Objects that have a small mass and a large volume have a low density.
Subject(s): Science
Grade Level(s): 8
Intended Audience: Educators
Instructional Time: 1 Hour(s) 40 Minute(s)
Freely Available: Yes
Keywords: mass, volume, density, float, sink
Instructional Design Framework(s): Guided Inquiry (Level 3)
Resource Collection: iCPALMS
LESSON CONTENT
Lesson Plan Template: Guided or Open Inquiry
Learning Objectives: What will students know and be able to do as a result of this lesson?
Students will be able to:
describe density
compare the densities of various materials using their masses and volumes
Content statements:
Density is the amount of matter filling the object's space.
Adding mass to an object without changing its volume, increases the object's density.
Objects that have a large mass and small volume have a high density.
Objects that have a small mass and a large volume have a low density.
Prior Knowledge: What prior knowledge should students have for this lesson?
From lower grades: SC.3.P.8.1, SC.3.P.8.2, SC.3.P.8.3, SC.3.P.9.1, SC.4.P.8.1, SC.4.P.8.2, SC.4.P.8.4, SC.5.P.8.1, SC.5.P.11.1, and SC.5.P.11.2
From this grade: SC.8.P.8.4
Mass – the amount of matter in an object
Volume – the amount of space that an object occupies
Guiding Questions: What are the guiding questions for this lesson?
Why do objects sink?...float?
page 1 of 3 What is the difference between the Diet Coke can and regular Coke can that explains why the diet one floats?
What variables can you change to make the canister rest at different levels in the water, and eventually sink?
What variables can you change to cause the grape to float?
Introduction: How will the teacher inform students of the intent of the lesson? How will students understand or develop an
investigable question?
Students are in groups of 3. Each chooses a number – 1, 2, or 3.
Show a regular Coke and a Diet Coke can (both unopened) to the class.
In their notebooks, students are to list how the two are similar. After a few minutes, randomly call on students to share their answers (the observations can be about
the outside of the cans or what they each contain – NO opinions). Then students create a T­chart to contrast the two. Again, have the students share answers with the
class.
Afterwards, tell the students that you are going to place the cans into a tank of water. The students write down what they predict what each can will do. (If a student
writes "One will float and one will sink," then tell the student to be specific-identify which can floats and which one sinks.) Have the students share their answers with
the group and come up with a consensus. #2's record the group's answer on the white wipe board. Randomly call on students to share their group's answers.
Put both cans in the tank of water. Students record their observations.
In their groups, students discuss why the Diet Coke can floated and the regular Coke can sank. #3's record the group's answers on the white wipe board. Randomly
call on students to share their group's answers.
Usually, through this sharing of answers, one group will say that the regular Coke has more stuff/sugars in it (or have more mass). Have enough cans of Diet Coke
and regular Coke so that each group can measure the mass of each kind. Again restate an earlier observation that they both have the same volume.
#1's write a conclusion statement explaining the differences in floating of the two cans.
Investigate: What will the teacher do to give students an opportunity to develop, try, revise, and implement their own methods to
gather data?
Each lab station should have a balance, a graduated cylinder, a beaker, a spoon, and salt.
Part A:
Groups go to their lab stations with their white board. Give each group an empty plastic canister (such as a film canister) into a beaker of water.
Ask: Why does it float?
Key Question: How can you make the container rest in the water at a different depths?
Students should work in their groups to create a plan – they are to write the plan on a white wipe board. Remind them to leave room to record their data (they should
take measurements to show what they changed and the results).
Part B:
Give a grape to each group. They are to put the grape into a beaker of water.
Ask: Why does it sink?
Key Question: How can you make the grape float?
Students should work in their groups to create a plan – they are to write the plan on a second white wipe board. Remind them to leave room to record their results.
(The students may come up with other ideas than salt for Part B so you should have a variety of materials available in case the students request it – sand, vinegar, oil,
honey, and a spoon with which to stir the materials if needed.)
Analyze: How will the teacher help students determine a way to represent, analyze, and interpret the data they collect?
Students should use the data tables to come up with a conclusion statement about each part of the lab that answers the questions:
What variables can you change to make the canister rest at different levels in the water, and eventually sink?
What variables can you change to cause the grape to float?
Closure: What will the teacher do to bring the lesson to a close? How will the students make sense of the investigation?
Direct instruction – define density
Think-Pair-Share:
What is the relationship between mass and volume for an object that has a high density?
What is the relationship between mass and volume for an object that has a low density?
After sharing, they are to write their answers in their science notebooks.
Exit card: Why is it easier to float in the ocean than it is to float in a pool?
Feedback to Students
The students will be provided feedback during the activities with questions and comments from the teacher. After the concept is taught (in closure), the students will
record answers to conclusion questions. In addition, the students will answer a question on exit cards, which can be returned to them later with teacher comments.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations: You may want to show the students an example of the grape floating in a cup of water (without telling them that the water has salt in it. If you
prepare the example a day or two ahead of time, you can supersaturate the water. Then, after the excess salt settles to the bottom, you can pour the salt water into
another cup (leaving the excess behind) and this minimizes the cloudiness of the water's appearance.
page 2 of 3 Extensions:
The teacher creates a drawing that shows 2 balloons on a scales balance – one balloon is up higher than the other (masses are unequal). Tell students that the
volumes of the balloons are the same and the number of molecules of each gas is the same in each balloon. (For example, one balloon is filled with air, the other is
filled with carbon dioxide – but don't tell the students the identity of the gases inside the balloons).
Ask: If the balloons' volumes are the same and there is the same number of gas atoms in each, why are their masses different? Are their densities equal or not?
Note to teacher: This synthesizes information regarding density and atomic masses.
Special Materials Needed:
White wipe boards with different colored dry erase markers
For Engage activity:
Diet Coke cans – 1 per group
Regular Coke cans – 1 per group
Clear demo tank or aquarium filled with water
For Explore activity – per group:
beakers
balances
salt
grapes
empty plastic containers (ie: film canisters)
water
SOURCE AND ACCESS INFORMATION
Contributed by: Lora Lindsey
Name of Author/Source: Lora Lindsey
District/Organization of Contributor(s): Marion
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.8.P.8.3:
Description
Explore and describe the densities of various materials through measurement of their masses and volumes.
Remarks/Examples:
Florida Standards Connections: MAFS.K12.MP.5: Use appropriate tools strategically and, MAFS.K12.MP.6: Attend to
precision.
Related Access Points
Access Point Number
SC.8.P.8.In.3:
SC.8.P.8.Su.3:
Access Point Title
Observe and compare the density of various materials.
Recognize that smaller objects can weigh more than bigger objects because of density.
page 3 of 3