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55-minutes
The ability of an object to float is generally controlled by two
properties: its density and its displacement. Objects that have
a density greater than water tend to sink. Objects that are less
dense than water tend to float. If an object displaces its own
weight in water, it will float regardless of its density.
Science
The learner will:
• estimate the volume of irregularly shaped solids
• predict whether objects will float or sink, based upon
their observations and calculations
• calculate the density of objects, using displacement method
National Science Education Standards
http://bob.nap.edu/html/nses/html
Content Standard B:
Properties of objects and materials
Louisiana Science Framework: State Standards for Curriculum
Development
http://www.lcet.doe.state.la.us/doe/assessment/standards/SCIENCE.pdf
PS-E-A1: Observing, describing, and classifying objects
by properties (size, weight, shape, color, texture, and temperature).
PS-E-A2: Measuring properties of objects using appropriate
materials, tools, and technology.
PS-E-A3: Observing and describing the objects by the properties
of the materials from which they are made (paper, wood,
metal).
Video:
Dr. Dad’s PH3: Buoyancy & Density
Web sites:
http://sm3a.gsfc.nasa.gov/hst_sm3A_gallery_nbltesting.htm
Astronauts prepare for space missions by training under water.
http://crawfishaquatics.com/swimming1.htm
This site relates the importance of buoyancy to our bodies ability
to swim & float.
http://www.ph.utexas.edu/~phy-demo/demo-txt/2b40-30.html
This site provides directions for developing a cartesian diver.
Per Class
• 3 Wide Mouth Graduated Cylinders (500 mL)
• 3 Large clear containers (pickle jars work well)
• 3 large non-breakable pans (pie pans, cake pan, etc.)
• Various fruits & vegetables
• 3 small toys
• 9 Miscellaneous small objects for measuring
• 3 tape measurers
• 3 balances
• 3 rulers
• 300 pennies or marbles
• 1 roll aluminum foil
Per Group
• Clipboard
• Activity Sheet
• Pencil
• Water
Per Student
• 1 – 12 inch sheet aluminum foil
1. CUE tape to the opening slates for the Dr. Dad
video, just pass the “Mark Twain” clip.
2. Prepare 3 stations:
• Large clear container
half filled with water
• Fruits
• Balance
• Tape measure
• Ruler
• Non-breakable pan
• Graduated cylinder |
|
|
• Large clear container
half filled with water
• Vegetables
• Balance
• Tape measure
• Ruler
• Non-breakable pan
• Graduated cylinder |
|
|
• Large clear container
half filled with water
• Toys/common objects
• Balance
• Tape measure
• Ruler
• Non-breakable pan
• Graduated cylinder |
3. Duplicate activity pages
SETTING THE STAGE
Students will work in small groups and visit 3 activity stations.
1. Students should be in their cooperative groups. Give the recorder
in each group a clipboard, activity sheet and pencil.
2. Students should be give one minute at the beginning of each
rotation to predict whether the objects at the station will sink
or float. Each group should come to consensus and the answer recorded
on the activity sheet.
3. When the students have made their predictions, they are now
ready to begin experimentation. The designated student should
slowly place one object at a time in the large, clear glass container
of water. They should also test each object more than once. Record
results.
4. Additional tools are placed in each station for students do
make additional discoveries. They should record their findings.
5. Compare each group results. What are the similarities and differences?
6. Ask students WHY they think that some of the objects floated
and some sank. Write their answers on the board or on flip chart.
Do not tell them the answer. Tell them that in the video, Dr.
Dad’s daughter was given that exact same question to answer
in school and that they are going to find out the answer by watching
the video.
1. START the Dr. Dad tape and PLAY
until Dr. Dad says, “What should we do? (5:12). PAUSE.
Ask students what they think should be done to the sinker to make
it float? RESUME video. PAUSE just before Olivia
actually puts the flattened sinker in the water. (5:55) Ask students
if they think that the flattened sinker will float or sink? RESUME
video and PAUSE at (6:18). Let students discuss what happened.
FAST FORWARD the video until Dr. Dad says, “While
we were talking…” (11:06). RESUME PLAY until
Dr. Dad completes weighing both of the sinkers and says, “Let’s
take a look.” (11:35) PAUSE the video. Ask students
to predict whether or not the flattened sinker will sink or float.
RESUME PLAY until the girls float their clay boat. STOP
video.
2. Tell students that they are
not going to build a clay boat like Olivia and her friends, but
an aluminum boat instead.
3. Give each student a 12 inch
long sheet of aluminum foil. If students wish to work in pairs,
that is acceptable. The challenge is to build a boat that will
hold the most pennies and still float.
4. Test the boats in the shallow
pans.
5. Have students discuss why some
designs floated and others did not and why some carried more pennies
than others.
1. Give each student a copy of the Density worksheet.
2. First have the students estimate
the volume of each of the objects. Record results.
3. Have students to fill the graduated
cylinder about half way with water and record the amount in milliliters.
4. Have students determine the
true volume of each object by carefully placing it in the water
and seeing how much the water rises above the starting mark. After
removing each object from the water, remind them to fill the cylinder
back up with any lost water and record any change in starting
volume.
5. After calculating the volume,
have students determine the mass of each item by placing it on
the gram scale or balance.
6. Students should calculate the
density of each object by using the formula Density = Mass
/ Volume.
7. Students should discuss their
findings and make predictions as to whether other objects will
float or sink.
Social Studies: Investigate the construction of Native
American canoes and the different materials used to build them.
• Many universities have spring “concrete canoe races.”
Contact the engineering department at a nearby university and
ask if someone from their department would talk to the class about
the boat design.
• Invite local boat and marine store managers to talk to
the class. The Department of Wildlife & Fisheries is also
a good resource on boating.
• Sink or Float Worksheet HTML PDF
• Density Worksheet
HTML PDF
