BUOYANCY OR WHAT FLOATS YOUR BOAT
Grades 5 - 8
In this lesson, students will learn as Bill Nye the Science
Guy discovers buoyancy. In this episode Bill Nye explores buoyancy through
cars that are boats, real and toy boats, personal flotation devices, SCUBA,
and human powered submarines. Students will observe two teacher demonstrations
of buoyancy and perform two hands-on activities that (1) when objects like
boats are placed in water they displace some of the water, (2) if an object
placed in water weighs the same or less than the amount of water it displaces
it will float, and (3) buoyancy also is responsible for allowing helium
and hot air balloons to float.
Bill Nye the Science Guy: Discovers Buoyancy
Students will be able to:
- determine the volume of water displaced by an object placed in water.
- determine the mass of water displaced by an object placed in water.
- identify that when the mass of water displaced is equal to or greater
than the mass of the object, the object will float.
- describe the rise of a hot air balloon in terms of molecular spacing
- determine the buoyancy of different objects in water.
- design a boat that will carry cargo.
- compare various boat shapes to cargo- carrying capacity.
"Coke Float" (Teacher Demonstration):
- one can Diet Coke
- one can regular Coke
- one two gallon transparent container of water
For each student:
- 1 Telecast Assessment Sheet (provided in Addendum)
"Pen Top Submarines" (Per student group of 2-4):
- one pen top
- one two liter bottle with cap
- marble-size ball of modeling clay
"Hot Air Balloon" (Teacher demonstration):
"What Floats Your Boat" (Per student group of 2-4):
- one plastic dry cleaning bag
- one electric hair dryer
- transparent tape
- 1 Buoyancy Homework Sheet FOR EACH STUDENT
- 1 "What Floats Your Boat" directions sheet (provided in
- 1 set of "What Floats Your Boat" data sheets (provided in
- one stick of modeling clay
- one container at least 500 ml capacity
- small masses such as washers, BB's, pennies, pinto beans, gram cubes
- one balance
The teacher will set up a demonstration that is designed to
pique student curiosity. Use an aquarium, or any transparent container,
that will hold at least two gallons. Fill it two-thirds full with water.
As class begins pass out the Telecast Assessment Sheet and tell students,
"Today I am going to show you an amazing sight. I have here two identically
sized cans of soft drink made by the same company. One is a diet drink and
one is a regular drink. What do you think will happen when I place each
of them in this container of water?" Allow time for students to respond.
Write their hypotheses on the board.
Teacher: "Now, observe carefully as I place each one in the water.
What is happening?" Write their observations on the board beside the
Teacher: "I would like for you to keep these hypotheses and observations
in mind and answer the PRE-VIDEO question on your Telecast Assessment Sheet.
We will return to our "Coke Float" after several days and see
if we can determine what may be responsible for our observations."
Each student will have a Telecast Assessment Sheet (TAS).
The teacher will go over the remaining questions/activities on the Telecast
Assessment Sheet. Begin the TAS review with "Be sure that you have
answered the PRE-VIDEO section of your Telecast Assessment Sheet. As we
watch "Bill Nye, The Science Guy, Buoyancy" we will stop and do
the INTERACTIVE section. After the video we will answer the POST-VIDEO section."
Go over all the question on the TAS.
Day 1: Start the video from the beginning, after the
PAUSE when Bill pours the water back into the boat mold.
Review with students that when an object like the boat is placed in water
it pushes the water out of the way.
PAUSE when Bill puts the water and the boat on the balance. Review
with students that the mass of water displaced balances the mass of the
PAUSE after the segment demonstrating the effect of shape on floating.
Review with students that shape makes a difference in floating and sinking.
PAUSE after the segment demonstrating a personal flotation device
(PFD). Discuss the question on the TAS concerning the buoyant force
stated on a PFD and allow students to arrive at the answer.
PAUSE after the "Try this" segment with the "Pen Top
Submarine." Have students do the "Try this Pen Top Submarine"
and answer the TAS question. End of Day 1. (If time becomes
a problem the "Try this" segment could be done at the beginning
of Day 2.) Collect the TAS.
Day 2: Return the TAS from Day 1. The teacher should
conduct a brief review of the previous day's lesson. If the "Try this
Pen Top Submarine" was not conducted on Day 1 do it now.
RESUME the video.
PAUSE after the segment where a "Hot Air Balloon" is demonstrated.
Do the teacher demonstration of the plastic bag "Hot Air Balloon."
RESUME and play through to the end.
Have students answer the TAS. Hand out the Homework Sheet
for "What Floats Your Boat." The Homework Sheet should
be collected following the "What Floats Your Boat" activity.
Day 3-5. The teacher will introduce the activity by returning
the scored Telecast Assessment Sheet and going over the answers to
the TAS found on the "Answer Key" for the TAS. To
complete this lesson return to the Coke Float hypotheses from the introduction.
Teacher: "Would you revise your hypothesis for the Coke Float based
on the Bill Nye, The Science Guy, Buoyancy episode?" Allow students
to elaborate on their answer to the question. Students may have suggested
a number of reasons for the observation that the diet drink floats while
the regular drink sinks. Among the usual suggestions are:
- one drink contains more caffeine than the other
- one drink contains more carbon dioxide than another
- one drink contains more volume than another
- sugar is heavier than sweetener
If the teacher doesn't wish to prolong the discussion and data collection
she could read the content labels on the cans to the students:
- state that the cans contain the same total volume
- state that artificial sweeteners weigh much less than sugar in equal
volumes and that the amount of sweetener used in diet drinks is much less
in volume than the amount of sugar used in regular drinks.
Therefore diet drinks are less dense, more buoyant, than regular drinks.
If the teacher desires, this activity can be extended for several days.
The drinks could be weighed. The drinks could be opened and the volume determined.
The drinks could be allowed to "go flat" to see if carbonation
was a cause.
Students could mass an equal volume of sweetener and sugar to compare mass
Students could determine the density of each drink.
Follow the Coke Float discussion with the "What Floats Your Boat"
Teacher: "Now, we are going to perform an investigation that examines
the concepts presented in the "Bill Nye, The Science Guy, Buoyancy"
video. Determine the size of student group you will use. This activity will
work well with student teams of four.
Pass out the directions and Data Sheet for the activity.
Teacher: "Let's begin by reading over the directions for the activity."
Read the activity sheet with the students. Assign duties to members of each
team: -primary investigator -materials specialist -data specialist -quality
Indicate the location where students are to pick up and return the materials
needed. Emphasize that students should pat dry the modeling clay with paper
towels and reshape it into a ball before returning it.
Set up a Class Data Table on the board or on an acetate for the overhead
projector. Students conduct "What Floats Your Boat" and report
their results on the Class Data Table and by completing the Activity
Sheet. This activity should take approximately 45-60 minutes to complete.
If it is necessary to break it up into two class periods have students collect
the data one day and analyze it to complete the Data Sheet the next. At
the end of class remind students that the Homework Sheet is to be
returned the following day.
On the following day the teacher will go over the class results from "What
Floats Your Boat." Discuss the designs that were most successful. Be
sure to allow students to provide their reasons for the designs that were
most successful. Be sure to allow students to provide their reasons for
the design's success. Collect the Student Data Sheets for each group.
Teacher: "Students take out your Homework Sheets. Exchange them
with other students on your team. Read over them in your group, then we
will have one member of each team report to the class on what your team
discovered." After team discussion one member of each team should give
a summary report of their results from the Homework Sheet.
An "Examples of Buoyancy" bulletin board could be
maintained in the classroom throughout the remainder of the school year.
A SCUBA diver could be invited to show students her gear and tell how the
concept of buoyancy is used in diving.
- Students could build and fly tissue paper of hot air balloons. Directions
- Students could learn and present the "Bill's Got A Boat"
rap. Text included.
- Students could develop a mini buoyancy lesson to present to students
in a lower grade.
Bill Nye, The Science Guy, Buoyancy "What Floats Your Boat"
Pick up the materials your group will need.
- modeling clay
- clear plastic container (the bottom part of a two liter bottle)
- metric ruler
Put a strip of tape on the outside of the container from top to bottom.
This will be where you mark the changes in water level.
Determine the mass of one of the objects you will use t o add weight to
your boat. Record this mass in the data table.
Fill the container two-thirds full of water. Make a mark on the tape strip
on the outside at the water level.
Make a ball of the modeling clay. Determine the mass of the clay ball. Record
the mass of the clay in the data table.
Drop it into the water. Mark the new water level on the tape. Use the ruler
to measure the change in water level. Record the water level change in the
Remove the clay ball. Brainstorm with your team to design a shape from the
clay that you think will float and hold the most weight. Sketch the shape.
Reshape the clay. Be sure to use the same amount of clay. Put your new clay
boat in the water. Mark the water level. Measure the change and record.
Predict how many pieces of cargo your boat will hold. Record your prediction
in the data table.
Test your prediction by adding cargo pieces to your boat. Each time you
add a piece mark the change in water level on the tape strip. Measure and
record the change in water level. Add cargo pieces until the boat sinks.
Pat dry your clay and weights. Return the materials.
Send one member of your team to record how many pieces of cargo your boat
held on the class data table on the board.
Graph the data you have recorded.
Answer the questions about the activity.
Master Teacher: Mary Alice Fryar
Lesson Plan Database
Thirteen Ed Online