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BURSTING METRIC BUBBLE
Grades 7 - 8

Overview

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.
ITV Series
3-2-1 CLASSROOM CONTACT: #123: Bubbleology
Learning Objectives
At the end of this lesson, the students should be able to:
Materials
(Note to teacher: See attachments for directions and diagrams.)

Surface Tension Mini-lab:
Teacher demonstration #1:
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.)

    Pre-Viewing Activities
    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:
    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.)
    Focus Viewing

    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.

    Viewing Activities

    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.
    Post-Viewing Activities
    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.
    Action Plan
    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.
    Extensions
    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:


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