BURSTING METRIC BUBBLE
Grades 7 - 8
This lesson is designed to liven up metric measuring while teaching
students about the surface tension of liquids. This lesson can be used with
units using the scientific method, predicting, basic geometry, properties
of water, measuring, recording, finding averages, circumference, and ratios.
Students will be observing surface tension, making predictions, forming
hypothesis, blowing bubbles using a straw on a table or desk top, measuring
diameter using centimeters and millimeters, recording information, calculating
averages, determining circumference, graphing, defining vocabulary, developing
group synthesis, making class comparisons and presentations.
Students will need a review of math terms, graphing, and measuring skills,
as well as an introduction to surface tension and relevant vocabulary. This
lesson will develop student skills in metric measure of straight lines,
calculating averages and circumferences in a hands-on cooperative group
activity. The length of time needed my vary from 2-4 class periods, depending
on the amount of review needed and the number of enrichment activities utilized.
3-2-1 CLASSROOM CONTACT: #123: Bubbleology
At the end of this lesson, the students should be able to:
- Define vocabulary terms related to metric measure of length, surface
tension, and basic geometry terms relating to a circle.
- Measure and record the diameter of a circle using metric measure.
- Calculate circumference of a circle.
- Determine the average the 3 measurements taken for each of the 4 bubble
solutions.
- Predict which of 4 bubble solutions will produce the bubble with the
largest diameter.
- Synthesize group information in preparation to make a chart.
- Create a chart with group information that includes a graph indicating
the individual and group results of the lab.
- Make a presentation of the results of group findings to the class.
- Synthesize which bubble solution, based on presented information,
produced the bubble with the greatest diameter.
- Hypothesize the ingredients for the unknown bubble solution. Give
an example of a ratio.
(Note to teacher: See attachments for directions and diagrams.)
Surface Tension Mini-lab:
- 1 penny per student
- 1 pipette or water dropper per student
- 1 small container of water per two students
Teacher demonstration #1:
- milk carton or tin can
- nail/hammer (for demonstration preparation)
Teacher demonstration #2:
2 beakers or glasses
1 piece of absorbent string 30 cm long
1 book
water (about 200 mL)
food coloring
"You're Full of Hot Air" Activity: (Materials are for entire class
except where specified.)
- 4 liter beakers (or large containers for solutions)
- Dawn dish washing detergent
- Joy (or Sunlight) dish washing detergent
- Bargain or store brand dish washing detergent
- 4 small plastic glasses or 80 mL beakers per group of 4 students
- 1 straw per student
- 1 metric tape (preferred) or meter stick per person if possible
- towels or paper towels to clean
- glycerin or corn syrup
- 1 gallon of distilled water
- geometric 3-dimensional bubble blowing devises (optional)
- large container for bubble solution (optional)
- 1 poster paper per group of 4
- 1 set of poster markers per 4
- 1 calculator per student or group (optional)
- 1 eyewash station (in case bubble solution gets into a students eye)
The day before beginning this activity and video, review basic
math terms relating to determining circumference of a circle using metric
measure.
Measuring unit - The known amount that is compared to an unknown
amount.
Measuring - Comparing a known amount with an unknown amount.
International System of Measurements - Universally
accurate system of measure used by almost all countries but the United States.
All scientists use this system so they can communicate their findings regardless
of the country they live in.
SI - Abbreviation of International System of measurements
Metric System - The common name of the International System of Measurements.
Prefix - The beginning part of a word that is used to describe the
term it is placed in front of. In this case, it will describe the measuring
units size.
Centi - Prefix meaning one-hundredth
Centimeter (cm) - Metric measuring unit that is one-hundredth of
a meter.
Milli - Prefix meaning one-thousandth
Millimeter (mm) - Metric measuring unit that is one-thousandth
of a meter.
Meter (m) - Basic metric unit for finding length. 39 and one
quarter inches.
Average - Finding the mathematical middle of more than one number
by adding the numbers together and dividing the sum of the total set of
numbers by the number of figures added.
Diameter - The measure of a line that divides a circle into two equal
halves.
Pi - The mathematical equivalent equaling 3.14. When pi is multiplied
by the diameter of a circle it will determine the circumference of that
circle.
Circumference - The measure of the outer distance around a circle.
Formula for finding circumference - pi X diameter = circumference
Tools of metric measure of length - Meter stick, metric ruler, metric
tape
Ratio - The relationship in quantity, amount, or size between two
or more things.
A review of terms relating to surface tension will also be needed. If these
are new terms and concepts, teacher modeling labs and one hands-on mini-lab
are included. However, it is through investigation and the video that the
term "surface tension" itself will be defined.
Adhesion - The ability of different types of substances to stick
together.
Cohesion - The ability of the same types of substances to firmly
hold together.
Surface - tension Students will derive this definition on
their own after the investigations and video presentations.] Surface tension
is a force. Forces act on something to make it do something it may not normally
do. In the case of the soap bubbles, the adhesive forces between the liquid
molecules and the solids (called adhesion) and the cohesive forces between
the molecules of the soap solution (called cohesion) cause the bubble solution
to take the shape resulting in the smallest surface area, which is a sphere,
or a bubble.
Note to teacher: Perform two simple demonstrations to illustrate cohesion
and adhesion. (See attachments)
Student Hands-On Mini-Lab: Surface Tension:
Note to teacher: There is no work sheet for this activity. It is
a spring board into the main hands-on activity to be done later.
Materials Needed:
- 1 penny per student
- 1 pipette or water dropper per student
- 1 small container (beaker or glass) of water per 2 students
Procedure:
Each student will predict how many drops of water they can fit on the face
side of a penny while it is resting flat on the table.
Each student will count one drop at a time as they release it from a pipette
or dropper.
QUESTIONS FOR
STUDENTS AND ANSWERS FOR TEACHER
Were you able to fit more or less drops on the penny than you predicted?
(Most likely, more.)
What shape did the water take before the last drop caused it to spill? (A
dome-shape convex meniscus)
What caused the water to stack so high as to create this shape? (Surface
tension due to adhesion of water molecules to the penny and cohesion due
to the water molecules attraction to each other.)
First Segment:
The focus for viewing is a specific responsibility or task (s) that the
students are responsible for during or after watching the video to focus
and engage students' viewing attention. It is important to let students
know it is acceptable (and desirable) to have them request you to pause,
stop or rewind the video so they can get the information you desire for
them to glean from the video.
Ask students if they can think of any other examples of water being stacked
into a dome shape. (Possible responses- water drops of condensation on a
glass, dew formed on a blade of grass or a leaf).
Ask students to watch for the definition of surface tension.
Second Segment:
Hand each student the FOCUS FOR VIEWING ACTIVITY SHEET.
Note to teacher: Read the following focus for viewing questions orally to
the class and discuss possible answers with them. This helps to sharpen
student awareness level as the answers are presented in the video.
What is surface tension?
Why do bubbles take the shape of a sphere?
What 3 ingredients are used to make a great bubble solution? What is the
ratio of these ingredients?
Why is it necessary to add this special ingredient to make longer lasting
bubbles?
Using two different diagrams, illustrate the different layers of a bubble
when first blown, and then again, after the bubble has been inflated (blown)
for awhile.
What can be done to the bubble blowing device to make the bubbles larger?
When using a prism frame, what causes the soap film to meet in the middle?
Does a bubble try to be round because of the air inside of it?
Does the shape of the frame alter the shape of the bubble?
What is the reasoning that supports your answer?
Direct the students attention to locating the answers to the questions on
the work sheet while watching the video. Encourage them to yell, "Pause,"
" Stop," or "Rewind," as often as they feel the need
to have you do so.
Refer to FOCUS FOR VIEWING ACTIVITY SHEET.
First Segment:
START the video immediately following the introduction/song of 3-2-1
CLASSROOM CONTACT.
PAUSE the video when the word "Bubbleology" appears. Ask
students what they think this word means. (Study of bubbles.) Ask students,
"How are bubbles like the water dome you created on the penny?"
Note to teacher: It may take them some time to realize any relationship.
If they do not, tell them they will know the relationship at the conclusion
of this lesson. RESUME the video.
PAUSE the video just after the girl wearing the red shirt explains
that surface tension is a force, forces make things do things, that makes
things stick to itself and pull it together. Ask students, "Who can
explain what surface tension is in their own words?" Elicit responses
from several students. RESUME the video.
PAUSE the video after you hear the term "bubbleologist."
Ask students what they think this word means. (A person who studies bubbles.)
RESUME the video.
FAST FORWARD to where you see a little boy in the audience
stand up for the second time and Richard says, "On that note..."
and you see the girl in the red shirt again. RESUME the video.
STOP the video when girl says, "I've just noticed something...bubbles
are round, Hmmm..." Then she grabs her chin. Do not rewind the video
if it is your last or only class. After the lab activity, you will resume
the video from this point.
Second Segment:
RESUME the video at the place you left off (right after the girl
in red grabs her chin and says, "Hmmm...").
Note to teacher: You will need to encourage the students to ask you to
pause or to rewind and replay the part of the video they need to see again
when the answers to the questions appear. This will be a new skill for the
students and many will be reluctant at first to do this.
You may wish to pause after the explanation that answers the first question
and check to see that the students were all able to get the information
written down. It may help to walk around (if you have a VCR remote) to ensure
that the students are getting the desired information from the video. Previous
experiences that required speed writing of notes during a video, with seemingly
little comprehension, will easily give way to this new methodology. You
will feel your students relax as you continue in this style.
Say, "According to the video, what shape are bubbles?"
(round, but spherical is a better response) "Since bubbles are spherical,
can anyone tell me how it would be possible to measure the diameter of a
bubble?" Wait for responses (students will usually be unable to come
up with any solution that you can not 'burst'!) Say, "The lab we will
be performing is an investigation of surface tension and the metric measure
of the diameter of a bubble. At the end of this class you will experience
the surface tension that was discussed on the video, and discover how to
measure the diameter of a bubble using the metric system."
Divide class into groups of 4 students each.
Teacher may assign individuals within each group certain responsibilities,
i.e., get materials, clean up, etc.
Give the following directions to the students: Place beakers or glasses
labeled (Solution) A, B, C, and D on each group table or one solution per
each of the 4 desks according to the diagrams below. Note to teacher:
Refer to attachments for diagrammed directions.
Make sure the solutions remain in the same place throughout the lab activity.
Make sure students are instructed to use the same end of the straw each
time (or the results will be bitter!)
Each student will blow 3 consecutive bubbles from each of the 4 solutions,
measuring diameter and recording the diameter on the lab sheet in centimeters
and in millimeters.
Show the students a straw and the four different bubble solutions and the
metric tape (or meter stick). Say, "I will now attempt to blow a bubble
with "Solution C" using this straw, and I will also be able to
measure the diameter of this bubble with this metric tape." Model how
to blow the bubble and measure the diameter of the bubble.
Note to teacher: Model blowing a bubble on a table top. Practice before
doing this in front of the class. It is very easy, but there is technique
to be developed if you are going to "Wow" them! Refer to the diagram
in the attachments.
Before you let the students begin the actual lab, hand out the "You're
Full of Hot Air" Activity Sheet. (See attachments)
Have students remove all objects from the table/desk area to prevent messes.
Remind students of lab safety procedures. Have an eyewash station, or sink
(with running water) available for any accidental splashes that may end
up in a student's eye.
Have the students record their predictions on the Activity Sheet of who
in their group will blow the bubble with the largest diameter and which
solution he or she thinks will result in the largest bubble diameter.
Each student is responsible to measure and record the diameter of his or
her 3 bubbles per solution on the Activity Sheet. Tell students averages
and circumference calculations will be determined during the next class
or assign Table A as homework.
Each student gets 3 practice bubbles at the solution where they are sitting.
After this initial practice, all bubbles that leave a circle when popped
are to be measured and recorded.
When all students in a group have finished, students may experiment to see
if two or more students can produce the same bubble at the same time, or
other variations. If you have the 3-dimensional bubble blowers, students
may investigate using these. (These are shown on the video. Plastic models
can be purchased through science supply catalogs, or you can find someone
who can weld to make them for you from coat hangers.)
Have students turn papers in or place into their folders (whatever is your
room procedure).
Clean up needs to begin 5 minutes before class releases if there is another
class to follow. The cups or beakers marked "A," "B,"
"C," and "D," need to be refilled and returned to tables
or desks.
Clean up needs to begin 10 minutes before class releases if this is the
only or last class. It takes lots of water to get bubble solution completely
off table/desk surfaces. Bath (gym) towels or terry-cloths work the best.
Have students place metric tapes (or meter sticks) in a designated area.
Pour remaining solution in main container with same letter. Reserve solution
if you plan to extend activity with 3-dimensional bubble blowing devices.
Note to teacher: See attachments for an example graph that may be presented
by students.
Note to teacher: After students have presented their group findings to
the class, most likely Solution C will be the solution that had produced
the bubbles with the largest diameters.
Have a local professional who works with metric measurements
in his or her field come into your class to discuss the importance of learning
the metric system. Possibilities could include someone in the medical profession,
a mechanic, or a technician from a laboratory or industrial institution.
Encourage each student to explain what surface tension is to his or her
parents, and with the parents help, find different examples of surface tension
that occur in nature.
If there is a hands-on science center in your area, make arrangements for
a field trip for the students in your class. Most centers have displays
on bubbles and surface tension.
Have students design and perform a bubble festival for students in a younger
grade.
Have students write and perform a bubble "rap" or song.
Have students write and perform their own video production to illustrate
surface tension or the importance of learning metric measure.
Math: Challenge students to discover how pi was calculated,
why pi equals 3.14, and what the complete calculation of pi really is.
Math and Science: Expand metric measure to include mass (grams), volume
(liters), density (grams/milliliters), and temperature (degrees Celsius).
Science and Math: Let students investigate different proportions and ingredients
that would result in the best super bubble possible. Make sure students
record each trial and the ratios for each solution.
Science: There are many investigations that can be facilitated in a lab
situation that can further explore surface tension, cohesion and adhesion.
Direct students to these resources, or let them develop their own demonstration/investigation.
Social Studies: Which countries are the only countries that do not use the
metric system? Students having access to on-line telecommunications could
correspond to students from other countries and take a survey of those countries
contacted.
Economics: Why is it important for the individuals living in United States
to learn about the metric system?
Art: Why are there so many colors reflected on the surface of the bubble?
History: Who originally established the metric system? When was it established?
History: When were bubbles first discovered?
Video available from
3-2-1 CLASSROOM CONTACT: #123 Bubbleology, and can be taped off of television.
Check ITV overnight schedule.
Lesson plan developed by Master Teacher Linda A. Brown, Parma Middle
School, Parma, Idaho
NOTE TO TEACHER
TEACHER DEMONSTRATION 1 - COHESION
MATERIALS NEEDED:
An empty milk carton or tin can and a nail/hammer to punch holes. A sink
or large container to catch the flowing water.
PROCEDURE:
Make three small holes in one of the sides near the bottom of the carton
or can - about 1/2 centimeter apart from each other.
Fill the container with water and observe the water streams coming out of
the holes.
Bring the streams together with the fingers, near or on the holes, to make
one big stream. Separate the streams by pushing one finger through the middle
of the large stream. (Both of these procedures need a little practice before
you demonstrate in front of the class).
QUESTIONS TO ASK STUDENTS WITH ANSWERS FOR TEACHER:
Why does the water stay in one stream once they are brought together? (Cohesive
forces of the same type of [water] molecules.)
Is it easier to cause the streams to come together with a full or almost
empty container? (The fuller the container the easier to separate streams,
but as the container gets lower, it is easier for them to cohese together.)
Can anyone tell me an example in everyday life where you could find this
actually happening? (We see this phenomenon in daily life in the shower
head with many holes in it. When the valve is turned wide open, separate
streams are easily distinguished. But when the valve is only opened partially,
the many small streams will cling together and form one large stream.)
TEACHER DEMONSTRATION 2 - ADHESION and COHESION
MATERIALS NEEDED:
- Two beakers or plastic cups.
- A piece of water absorbent string or thin rope (cotton type is best)
- (Length depends on how much you practice! Begin with about 30 centimeters)
- 200 mL water with a couple drops of food coloring for easier viewing
- A science textbook
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