I'VE GOT THAT SINKING FEELING
Grades 6-8
In this lesson and its hands-on activities, the students should
have the opportunity to design a simple boat and predict how much weight
it can carry. The students should also discover why objects float or sink
and how this can be determined experimentally. The students should gain
experience in data collection, conclusion formation, and analysis skills.
Bill Nye The Science Guy #119: Buoyancy Mr. Wizard: How it Works: Buoyancy
Science Demonstrations #13: Archimedes' Principle Dr. Dad PH3 #2: Buoyancy-Sink,
Float or Boat
Students will be able to:
- collect data
- state why some objects sink and others float
- design a simple boat from aluminum foil and determine how much mass
it will hold
- analyze how the density of a liquid affects its buoyant force
- construct a submarine in a bottle
- write conclusions based on experimental evidence
- make predictions based on experimental evidence
- define Archimedes' Principle
- and use listening and note-taking skills to complete a guided listening
sheet
Per class:
- water supply
- 2 glass cylinders
- grapes and mothballs
- several Alka Seltzer® tablets
- 1 or 2 cans of Mountain Dew® soda
- cubic centimeter made from paper
- plastic pipette
- water soluble marker
- cleaning cloth
- equal volumes of mercury and water in sealed containers
- guided activity sheets
- prepared supply dispersal and collection chart
Boat construction activity:
Per group of students:
- aluminum foil sheets precut into 6 inch squares
- supply of pennies or paper clips
- bowls
- paper towels
- balance
Submarine construction activity:
Per group of students:
- plastic bottle with cap but without label (half liter through 2 liter
size) modified micropipette with hexagonal nut attached
- blue, red, yellow, and green food dye
- large bowl of water
Post-Viewing Activity Per group of students:
- wax paper squares
- clay
- supply of paper clips,
- marbles or pennies
- bowl
- balance
- Archimedes' Principle - Any object floating upon or submerged in a
fluid is buoyed upward by a force equal to the weight of the displaced fluid.
- fluid--matter that flows
- graduated cylinder - device that measures the volume of a liquid milliliter
- volume measurement equivalent to a thousandth of a liter
Before beginning this activity, students should understand the
concept of density.
A few minutes prior to the beginning of class, place on your desk two tall
clear cylinders. Fill one with water and place a drop of blue food coloring
in it. Fill the other with Mountain Dew® soda. As the students arrive,
place several mothballs and two Alka Seltzer® tablets in the water cylinder.
Place several peeled and unpeeled grapes in the soda cylinder.
Allow the students five minutes to make careful observations about the two
cylinders and to write their detailed, descriptive observations on a piece
of paper. Choose several students to share their observations with the rest
of the class. Ask the students to explain why some objects moved while others
didn't. Explain the preceding situation this way: the peeled grape has no
attraction for the bubbles. This type of surface is called hydrophilic (or
"water-loving") and attracts only the water. The bubbles could
not stick to the surface. The moth balls and the regular grapes have a hydrophobia
(or "water-fearing") surface. This surface repels water and gives
the bubbles a surface to adhere to. When enough gas bubbles have adhered
to the surface of the grapes or mothballs, they float. When the mothballs
and grapes reach the surface, the bubbles burst and the objects sink. Ask
the students to predict what the bubbles were made of in each cylinder.
(Carbon dioxide gas should be the answer.)
The focus for viewing is a specific responsibility or task(s)
students are responsible for during or after watching the video(s) to focus
and engage students' viewing attention. In this activity, the focus for
viewing is a guided listening sheet that the students are required to complete
during the course of watching the video.
Explain to the students that today's lesson is entitled "I've
Got that Sinking Feeling." Ask if anyone knows what buoyancy is (the
upward push of a fluid). Ask the students to give examples of situations
where they might have encountered buoyancy. (Accept all answers without
giving the definition of buoyancy. If students do not respond to the question,
tell them to watch the following video to learn the answer.) Distribute
the guided listening sheets. Tell the students to look over their listening
sheet carefully and notice how it is arranged. The first part of the sheet
deals with data collection and organization. They will fill this out as
they view an experiment on video. The rest of the sheet requires that they
pay close attention to various videos and activities in order to obtain
the correct answers.
INSERT Bill Nye The Science Guy #119: Buoyancy and start the
video after the announcer says, "Bill Nye the Science Guy is brought
to you by boats." PAUSE the video after Bill Nye says "Buoyancy's
a great thing. It's holding us up right now." Ask a student to define
buoyancy. RESUME the video. PAUSE after Bill Nye says "How
much do you think the water weighs?" Ask students to suggest an answer.
RESUME the video. Use a water soluble marker to mark on the TV screen
and emphasize the indentation left by the boat as Bill Nye fills it up with
the blue displaced water. STOP and EJECT the video after Bill
Nye says "It fits exactly. Isn't that cool?" Erase the TV screen
with a cloth.
INSERT and START Mr. Wizard How it works: Buoyancy.
STOP the video when the girl fills in 600 grams and Mr. Wizard says
"As you know, one milliliter of water weighs one gram." Ask the
students if the mass of one milliliter of any liquid is equivalent to one
gram. (No, this is a special relationship with pure water at 4 degrees Celsius.)
Reinforce this concept by asking a student to use a balance and determine
the mass of a graduated cylinder. Instruct the student to add exactly one
milliliter of water to a graduated cylinder by using a plastic pipette.
Ask the student to read the new mass on the balance for the class. Reinforce
this concept by asking the student to tell the class the mass of one milliliter
of water (one gram). Show the students the prepared cubic centimeter paper
box. Ask another student to pour the milliliter of water from the graduate
into the cubic centimeter box and make an observation. Ask the student to
share the observation with the other students. (One milliliter of water
fills up the cubic centimeter box.) Tell the students that a relationship
exists with water. One cubic centimeter of water is the same as one milliliter
of water and the mass of the water is equal to one gram.
RESUME the video. PAUSE after the difference data is filled
in on the chart, then ask students to analyze the data and make a conclusion.
Tell the students to write a conclusion about floating objects and the water
they displace on their data sheets. Call on a few students to read their
conclusions. RESUME the video to hear Mr. Wizard's explanation. (If
something floats, then it displaces an equal volume of water as it weighs.)
REWIND and play the video if the students need to hear the explanation
again.
RESUME the video. PAUSE the video when the girl writes in
100 grams. Ask the students to analyze the data on sinking objects and write
a new conclusion. Call on a few students to read their conclusions. RESUME
the video to hear Mr. Wizard's explanation. (Even though an object sinks,
it is still buoyed up by an amount of water equal to its displaced weight.)
REWIND the video if students need to hear the explanation again.
STOP and EJECT the video when Mr. Wizard says "Well,
you've got the idea and you did a beautiful job on the chart."
At this point, let the students know that they, as teams, will be designing
boats, using aluminum foil, that will float.
Prior to class, create a supply dispersal/collection chart. To prepare this
chart, divide a large piece of poster board into as many sections as there
are groups. Outline and number each section clearly with a marker. Cover
the entire board with clear contact paper. Place the necessary supplies
for each team of students in the numbered squares. Assign each team of students
a number and tell them to obtain their supplies from their numbered square
at the supply table. Tell them to follow the instructions on their worksheets
and complete the data table. When they are finished they should replace
their materials on the assigned group number on the supply chart. When the
activity is completed, check to see that each group returned their materials
as directed.
Ask them to predict whether objects will float in liquids other than fresh
water? (Boats float in salt water.) Ask them if salt water is heavier than
fresh water. (Yes, it has a higher density.) Ask if an object has to displace
more or less salt water than fresh water in order to float?" (Less)
Show the students two containers that contain identical volumes of liquids.
Tell them one contains mercury and the other water. Pass these sealed containers
around the room, allowing the students to feel the difference in weight
between equal volumes of water and mercury. Ask, if they think anything
can float in mercury. Accept all answers.
INSERT Science Demonstrations #13: Archimedes' Principle.
START the video after Dr. Miller says "I'm going to put the
ball in the vessel of mercury." PAUSE the video and ask the
students to predict what will happen. RESUME the video and MUTE
the volume when Dr. Miller says "What about steel?" Muting the
volume at this point will focus the students' attention on the steel ball.
Ask for predictions on what will happen to the steel ball.
PAUSE the video momentarily just before the steel ball is placed
into the mercury. This creates a suspenseful situation with the students.
RESUME the video and correct the volume. STOP and EJECT
the video after Dr. Miller says "Now talking about Archimedes."
Ask if anyone ever heard of Archimedes and his principle. Tell the students
that Archimedes lived in the third century B. C. and discovered that an
object's volume can be calculated by the amount of water it displaces. He
discovered this while he was bathing and became so excited he jumped out
of his bath shouting 'Eureka! Eureka!' and ran down the street naked. His
principle states that any object floating upon or submerged in a fluid is
buoyed upward by a force equal to the weight of the displaced fluid. Ask
students to define a fluid. (Anything that flows) Tell them this means that
gases as well as liquids are fluids because they flow. Hot air balloons
rise when they displace their weight in air and boats float when they displace
their weight in water.
INSERT Bill Nye The Science Guy #119 : Buoyancy and FAST
FORWARD to the "Try this section" on making your own submarine
in a bottle. Fast forwarding will eliminate the parts of the tape that are
not applicable to this lesson. STOP and EJECT the video at
the end of the explanation on fish bladders. At this point, announce to
the class that they will now construct their own submarine in a bottle.
Use the idea from Bill Nye or use the following method to construct a low-cost
submarine that the students may take home. Prior to class, obtain small
plastic micropipette and cut all but one centimeter off the drawn tip.
Insert a small hexagonal nut on the cut tip of each pipette. If it is not
a secure fit, use a glue gun to secure the nut in place. The nut gives the
pipette ballast when placed in the water.
Distribute one plastic bottle and one modified pipette to each student.
Tell the students they may use food coloring to color the water in their
bottles. Show the students how to fill their pipettes three-quarters full
with tap water. (Place pipette upside down in a container of water and squeeze.
Water will enter the pipette when the pressure is released.) Show them how
to check if their submarine will operate correctly by placing it in a tub
of water. The pipette should float in the water. If the pipette sinks, the
students should squeeze out some water. If the pipettes rises too high in
the water, they should add some water. Tell them to fill up their bottles
to the rim, insert their submarines, and put the caps on. Carefully examine
the pipette diver as pressure is applied to the bottle. Ask students what
they think makes the submarine move up and down in the bottle. (As the bottle
is compressed, water enters the diver and makes it less buoyant.) Instruct
the students to clean up their work area.
Tell the students that since they know why a boat floats and how air can
be adjusted in a submarine to raise or lower it, they should be able to
determine whether boats can be made of any material. Accept all opinions
from the students.
INSERT Dr. Dad's PH3#2: Buoyancy - Sink, Float or Boat. START
the video at the beginning of the canoe race. MUTE the volume in
order to focus the students' attention on the design of the boat after the
girl says "We just took this canoe to state championships and we are
in first place in all the races and design and everything." Tell the
students to make careful observations on the canoe the girls are carrying.
PAUSE the video when Dr. Dad and the two girls sit down. Ask if this
is an ordinary canoe. Ask if they notice anything special about its shape,
design or material. RESUME the video and correct the volume so students
can hear the girls discussing the various aspects of their canoe. PAUSE
the video after the girl says "Concrete can be molded into any shape
and it can hold." REWIND the video and play this part back if
students need to review.
PAUSE the video after Dr. Dad says "How do you get concrete
to float?" Ask the students if anyone can answer that question. RESUME
the video to hear the answer. STOP and EJECT the video after
the girl says "That's Archimedes' Principle."
Collect the guided listening sheet and take a grade on it. Remind
them that in today's lesson they learned why a boat floats and how a submarine
dives through the water. Tell them that now it is their task to design a
boat that will hold at least three times its mass in cargo. Hand out the
post-viewing activity sheet entitled Some Boats Won't Float. Tell them they
may use either wax paper or clay to construct their boats. After designing
and constructing the boats, all questions on the activity sheets must be
answered. Assign each team a number and tell them to mark their boat with
their number and place their finished boat on the supply dispersal sheet
when they are finished.
Allow the students access to the following building materials: wax paper,
clay, bowls and water. Have several balances available for students, along
with loading objects such as marbles, pennies or paper clips. Allow the
students 10-15 minutes to construct their boat. After all boats have been
constructed, instruct each student team the task of testing the boats of
two other teams to see if they have met the criterion of holding at least
three times its mass in loading material. Observe each team as they construct
and test boat models. Ask if any team feels they have a boat that can hold
more than three times its mass in cargo. Challenge all teams to discover
the maximum load capacity of their boat. Remind them to follow the instructions
on their activity sheets to discover the maximum load capacity of their
boats in relation to their mass.
The design of the boat that can hold the most cargo can be analyzed by the
class. (This design displaces the maximum amount of fluid.) Instruct students
to clean up their work areas. Collect activity sheets when the class is
finished.
Take a field trip to a boat-building facility to see how boats
are designed and made.
Ask a boat builder to visit class and to explain how designs are created
and how boats are built.
Have a Navy spokesman visit class to discuss warships and submarines.
Art: Students can draw pictures of boats or create boats from
paper.
Engineering: Students can create and design a boat from cardboard that must
hold a person and move in water at least 500 feet.
Geography: Students can research how geographical features influence boat
construction. Students can determine if salt water boats are designed differently
from fresh water boats.
History: Students can research the Titanic disaster or the life of Archimedes.
Language Arts: Students can write a story about life on a submarine or boat.
Math: The volume of actual row boats, canoes and kayaks can be mathematically
calculated.
Science: Students can observe boats in a nearby lake. They can analyze how
design and use of boat are related. Students can make notes on what types
of designs provide a maximum load capacity.
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worksheet associated with this lesson.
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