4 HOLT PHYSICS Laboratory Experiments

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Invention LabBubble Solutions

1HOLT PHYSICS

Post-ChapterActivity

Tantrum Toys, Inc.

T r o y , N e w Y o r k

August 15, 1999

Ms. Elaine Taylor

Product Development Department

1% Inspiration Laboratories

14557 West Post Road

Tempe, Arizona 85289

Dear Ms. Taylor:

At Tantrum Toys, we always try to stay one step ahead of the market. That’s

why we are looking into new formulations for our famous bubble solution. We

have developed a new formula that we believe will help our bubble solution

make bigger, longer-lasting bubbles.

We would like you to test our new bubble solution against several other

commercially available solutions, including the solution currently marketed by

Tantrum Toys. In order to cut down on human error or bias in the laboratory,

we are sending the solutions to you in identical packaging, marked only with a

letter. We would like you to test all solutions to find out which produces the

biggest bubbles.

Please perform two tests: the dome test and the free-floating bubble test. For

the dome test, use a straw to blow a domed bubble in a pan of solution.

Measure the height and diameter of each dome. For the free-floating bubble test,

construct a bubble maker to make large free-floating bubbles. Measure the diam-

eter of each bubble.

When you have finished your tests, put together a report describing how

you performed the tests, showing the equipment you used, and detailing your

results. Please have the report and all unused solutions delivered to my office by

September 8.

Good luck,

Stewart Clydesdale

A description ofa bubble makeris on page 6.

Stewart Clydesdale

CHAPTER 1 5

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MEMORANDUM

Date: August 19, 1999To: Product Testing TeamFrom: Elaine Taylor

I think the best way to get all these tests done in time is to have several

people work on them at once. Hopefully, one solution will be obviously bet-

ter than the others and all our results will be the same. Before you go into

the lab, prepare a plan for each of the tests described in the letter. Be sure to

include your plan for measuring the width, height, and diameter of the

bubbles in the lab. This will be a tricky procedure, because we have to find a

way to get good measurements without actually touching the bubbles.

Consistency and accuracy will also be very important, especially since we

will have to work quickly and carefully to make our measurements before

the bubbles pop.Present your plan to me for approval before you start work in the lab.

For each test, your plan should include a list of materials needed, a diagram,

and a one- or two-sentence explanation of the procedure you will use. I

have included a list of the equipment we have available. If you need some-

thing that you can’t find on the list, be sure to ask about it; there may be

more equipment available.For the second test, you will need to construct a bubble maker using the

materials on the list. The background information Mr. Clydesdale sent me

on one type of bubble wand is attached to this memo, but I will be interest-

ed to see what you can come up with. Be sure to include your design when

you submit your plan for approval.When you have all your results, write a report using the format of a

patent application. Remember to document all your testing and develop-

ment procedures in your lab notebook.

14557 West Post Road • Tempe, Arizona 85289

1% Inspiration Laboratories

See next page

for

safety requirem

ents,

materials list,

and

more hints.

continued

6 HOLT PHYSICS Laboratory Experiments

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MATERIALS

ITEM QTY.

✔ adhesive tape 1 roll✔ aluminum pans✔ bubble solutions✔ cord 100 cm✔ meterstick 1✔ metric ruler 1✔ paper towels✔ plastic drinking straws 6✔ rubber bands 4

SAFETY

• Do not eat or drink anything in the laboratory. Nevertaste chemicals or touch them with your bare hands.

• Dispose of chemicals as instructed by your teacher.Never pour hazardous chemicals into a regular wastecontainer.

• Tie back long hair, secure loose clothing, and removeloose jewelry to prevent their coming into contact withhazardous chemicals.

• Wear eye protection. Keep chemicals away from eyes.

It may not seem like a muse-um piece to some people,but to the children who visitThe Discovery ScienceMuseum in Birmingham, asimple contraption made ofplastic drinking straws andstring is among the best thingsthe museum has to offer.

This device allows studentsto make soap bubbles biggerthan any they’ve seen before.This magic wand was invent-ed right here at the DiscoveryScience Museum, but it can be

recreated by children every-where because the materialsare readily available.

All you need is a piece ofthread about 1 meter long andtwo plastic drinking straws.Thread the string through bothstraws, and tie the two ends ofthe string into a knot. Pull thestring around until the knot issafely hidden away inside oneof the straws. Use both handsto pull the straws apart, so thatthey are parallel to each other,with the strings relaxed

between them. Dip the twostring sides into bubble solu-tion—either a commercialbrand, like the favorite fromTantrum Toys, or a solutionmade with ordinary dish soap.

To make a long bubble,pull the frame through the airor blow gently. This activitywill delight children immedi-ately, but we bet it won’t takeadults long to admit that it is agreat work of art!

When it comes to bubbles, the bigger the better

HOLT PHYSICS Laboratory Experiments Teacher’s Edition

Invention Lab 1Post-ChapterActivity

Bubble Solutions

T28 HOLT PHYSICS Laboratory Experiments Teacher’s Edition

OBJECTIVES

Students will

• use appropriate lab safety procedures.

• use the scientific method to solve a problem.

• design and implement their own procedure.

• identify dependent and independent variables in

an experiment.

• work quickly to take accurate measurements.

PlanningRecommended Time

2 lab periods

Students should have their plan approved before the

class begins.

Materials

[for each class]

✔ 24 L water

✔ 50 mL glycerin

✔ 6 large aluminum pans

✔ 6 types of dish soap, 120 mL each

✔ newspapers

[for each group]

✔ 1 m cord

✔ 6 plastic drinking straws

✔ adhesive tape

✔ construction paper templates (see Proposed

Procedure)

✔ meterstick

✔ metric ruler

✔ paper towels

✔ rubber bands

Materials Preparation

Use six different types of dish soap for this lab,

including several national brands and one or two

local or store brands. You may also include one sam-

ple of automatic-dishwasher or laundry detergent,

for added interest. Prepare detergent mixtures at

least 24 h before they will be used to allow the glyc-

erin to dissolve. It is convenient to mix the solutions

in the storage bottles. Plastic milk jugs and plastic

soda bottles work well. Label each mixture with a

letter, and record the identity of each letter in your

notebook. You will need about 4 L of each solution.

For each liter of solution, use 30 mL of detergent,

2 mL of glycerin, and 1 L of water. Mix the water and

detergent first, then add the glycerin using a gradu-

ated dropper.

Be careful when mixing and storing glycerin and

glycerin solutions. Glycerin is combustible when

exposed to heat, flames, or strong oxidizers.

At the beginning of class, pour each mixture into a

large pan and label the pan with the letter from the

bottle. If you will be using the detergent mixtures for

two days, cover the pans to prevent the composition

of the mixtures from changing due to evaporation.

Classroom Organization

• Set up the mixtures at six stations so students can

move from station to station during the lab.

• Set out newspapers and paper towels on the lab

tables and floor to aid in cleaning up spilled

detergent mixtures.

• If possible, do this lab outdoors.

• Safety warnings: The floor will become very slip-

pery when detergent mixtures are spilled or

dripped. Make sure students exercise care when

moving around the lab. Remind students to clean

up all spills immediately.

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HOLT PHYSICS Laboratory Experiments Teacher’s Edition continued

CHAPTER 1 T29

Techniques to Demonstrate

Based on the plans students present before the lab,

you will be able to determine whether they need to

see a sample bubble maker for the second part of

the lab. You may prepare one according to the

design described in the lab and make it available for

students to look at. You may want to demonstrate

using the device to make bubbles, especially if you

are concerned about time.

Pre-Lab DiscussionDiscuss with students how they will know which

mixture makes the biggest bubbles. Ask students

what they mean by “size” in this lab. Most students

will realize that the size of the bubble is directly

related to the radius or diameter of the sphere.

Students should realize that they will need to find

the average bubble size for each mixture and that

they must be consistent in their measurements.

Tips for Evaluating the Pre-LabRequirements

Students’ plans should include both parts of the lab,

the dome bubble test and the free-floating bubble

activity. Complete plans will include a materials list,

a diagram showing the bubble-making apparatus

and a method for measuring the bubbles, and a brief

description of the procedure for each part. Plans

should also explain how students will analyze data

to determine which mixture consistently produces

the biggest bubbles.

Proposed ProcedurePart I: Domed Bubble Test

Use a plastic drinking straw to blow a dome bubble

in the pan of solution. The bubble will be half-

spherical in shape, so that the surface of the solution

is the base of the domed bubble. Blow several test

bubbles to determine how large the bubble can be.

Make the bubbles larger and larger until they burst,

and use this method to find the largest size of bub-

ble that will not pop.

There are several methods that can be used to mea-

sure the bubbles. Students may use templates made

from sheets of construction paper with holes of var-

ious diameters cut in them. They may also construct

a bubble meter using a meterstick with a crossbar

made from a drinking straw attached with rubber

bands. The crossbar can be moved up and down to

gauge the size of the bubbles. A meterstick can be

used with two straws, tape, and rubber bands to

make calipers to measure the bubbles. One straw is

fixed in place at the end of the meterstick, and the

other straw is attached with a rubber band so it can

be moved up and down.

Students may come up with other methods.

For each method described above, the easiest way to

find the maximum bubble size is to set the gauge to

a predetermined size and blow bubbles to fill the

gauge. Progressively increase the size of the gauge

until bubbles pop before reaching the gauge.

For each mixture, repeat the process of finding the

largest possible bubbles. Do several trials for each

mixture, and take the average of all trials to find the

average size of the domed bubble for each solution.

Part II: Free-floating Bubble Test

Design and construct a bubble maker using two

plastic drinking straws and a length of cord.

Perform several trials to find the best technique for

making large bubbles with the device. For some stu-

dents or some mixtures, it will be easier to make

large bubbles by gently blowing through the device

than by pulling it through the air. Students should

repeat the exercise until they are able to produce

consistent results for several trials.

At the same time, test and develop a method of

measuring the bubbles using a meterstick. This

method must take into account that the bubbles are

fragile, round, and in motion.

The meterstick gauge and meterstick calipers meth-

ods described above will both work to measure

these bubbles.

Students may come up with other methods.

Do several trials for each mixture, and take the aver-

age of all trials to find the average size of the free-

floating bubble for each solution.

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HOLT PHYSICS Laboratory Experiments Teacher’s Edition continued

T30 HOLT PHYSICS Laboratory Experiments Teacher’s Edition

Post-LabTips for Evaluating Patent Application Lab Report

Student lab reports should include diagrams of the

apparatus used to create bubbles and detailed dia-

grams of the method used to measure the bubbles.

Diagrams should be labeled and clearly drawn, and

there should be a section describing each diagram.

Reports should include an analysis of the method

and of the data. Students should describe how their

method of measurement overcame the problems of

measuring the bubbles consistently, and they should

analyze any error in their results.

Students should identify which mixture(s) produced

the largest bubbles and should explain the data

analysis they used to compare results for different

mixtures. Although individual results will vary, class

results on the whole should indicate that one or two

of the bubble mixtures produced the largest bubbles.

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Additional Notes