## Earth & Space Science: Holding it Together Grades K-2 or 3-6

This lesson explores surface tension and its effects on water and bubbles. Students will examine some of the amazing occurrences caused by surface tension.
3-2-1 Classroom Contact #23 "Surface Tension: Bubble-ology"
Students will be able to:
• Identify surface tension as a force
• Explain that a force causes something to happen
• Identify surface tension as the force that makes bubble solution molecules stick together
• Illustrate the various shapes of the bubble tools (grades K-2)
• Identify the shape of all bubbles as round (grades K-2)
• Describe how surface tension pulls a bubble into a sphere (grades 3-6)
• Identify the layers that "make up" a bubble (grades 3-6)
• Explain why glycerin helps bubbles last longer (3-6)
• Measure the diameter of the "table" bubbles (3-6)
• Predict the life span of a bubble.
For each student: (Grades K-2 or 3-6)
• 1 penny
• 1 eyedropper
• paper towels
• small cup of water (3 oz.)
For the class: (Grades K-2 or 3-6)
• 1 gallon of bubble solution (recipe below), in a plastic container; empty milk containers work well
NOTE: Bubble solution recipe
• 1 gallon of water (distilled works best)
• 1 cup of dishwashing soap
• 6 ounces of glycerin
• newspapers for the floor
• spray bottle of vinegar
• squeegee
For each student: (Grades K-2)
• bubble-making tools of odd shapes, to be made of clothes hangers or thin wire; kitchen tools with holes, such as potato masher, garlic press, or slotted spoon; pipe cleaners
• 2 straws
• 30 cm of string
• containers for bubble solution, large enough for bubble tools and frames, such as plastic shoe boxes
For each student: (Grades 3-6)
• 1-2 plastic drinking straws
• White paper collars (Directions for making located before the Action Plan of this lesson.)
• 12" by 18" paper
• small plastic cups to hold solution (3-5 oz.)
• plastic rulers or yardsticks
VOCABULARY:
• Shape - the visible characteristic of a particular object, type of object, spatial form
• Surface tension - a condition that exists at the free surface of a body (as a liquid) by reason of intermolecular forces about the individual surface molecules; manifested by properties resembling those of an elastic skin under tension
• Solution - a homogeneous mixture formed by mixing two or more substances
• Film - a thin skin or membranous covering
• Force - strength or energy exerted or brought to bear; cause of motion or change
• Frame - something composed of parts that are fitted together
• Round - in a circular or curved path or progression
• Sphere - a globular body; ball
• Glycerin - a sweet, syrupy substance, sometimes used to treat chapped skin.

Give each student a paper towel, a penny, an eyedropper, and a small cup of water. They are to predict how many drops of water they can put on a penny before it spills over. Write the predictions on the chalkboard. After the predictions have been made, direct the children to put drops of water on the penny and count the drops until the water spills over the side. Students will share how many drops they put on their penny and compare these numbers to the predictions they made.

NOTE: Very young students may need to practice with the eye droppers before doing this activity, and older students should try the experiment several times to obtain accurate results.

TEACHER: Why do you think the water was able to stack up on the penny like it did? (Allow the students to share a few possible answers.) Today we are going to watch a part of a video that will help us to understand how the water could do that.
It is important to give students a specific responsibility while viewing. Knowing what they are expected to learn allows them to focus on specific information and concepts in the video.

TEACHER: Today we will be learning about how surface tension works. We will be talking about bubble solution. We need to know what bubble solution is. Someone help us describe it. (Allow time for descriptions.) It is a mixture of water, soap, and a substance called glycerin. What do you see stretched across the hole when you dip a bubble-making tool into bubble solution? (Let students speculate about this. Lead them or tell them that this is called a film.) How does it make bubbles? (Allow them to voice a few ideas.) Listen to Stephanie and be able to tell us what makes soap film stretch and cling.
VIDEO: 3-2-1 Classroom Contact #23 "Surface Tension: Bubble-ology"

START video after the opening logo as Stephanie appears.
PAUSE after Stephanie says "surface tension."

TEACHER: What makes this thing called soap film stretch and cling? (Surface tension.) Listen and be able to share with the class what surface tension is.

RESUME video.
PAUSE after Stephanie says, "Surface tension is a force."

TEACHER: What is "surface tension?" (A force.) OBJECTIVE 1. Now be able to tell us what a force does.

RESUME video.
PAUSE video after Stephanie says, "Forces make things do things."

TEACHER: What do forces do? (Make things do things. To demonstrate this, place an object, such as a ball or a marker, on a table, and ask the students how to make the object move. They should tell you that you could push it and make it roll. Explain to students that the push is the force that makes the object move.) OBJECTIVE 2.

TEACHER: Listen and be able to share what the force of surface tension does to bubble solution.

RESUME video.
PAUSE video after Stephanie says, "It makes bubbles."

TEACHER: What does surface tension do to the bubble solution? (Makes it stick to itself, and make bubbles.) OBJECTIVE 3.

STOP video here and go to the Post-Viewing Activities.

CONTINUE. This section concentrates on students gathering and checking information.
FAST FORWARD through the bubble festival to the place Stephanie reappears.

TEACHER: Watch what happens when Stephanie breaks the surface tension inside of the thread.

RESUME video.
PAUSE video after Stephanie says, "Success!"

TEACHER: What shape does the thread make? (Round.) Now listen to Stephanie's explanation of why this happens.

RESUME video.
PAUSE video after Stephanie says, "Surface tension pulls the string into a circle."

TEACHER: Why was the thread pulled into a circle? (Surface tension.) Listen and watch to be able to share about Stephanie's problems as she first tries her experiment, as well as her solution to the problems.

RESUME video.
PAUSE video after Stephanie says, "That's science!"

TEACHER: What were Stephanie's problems? (String too thick, frame too large.) What did she do about them? (Kept trying different things until the experiment worked.) Listen and watch for what Stephanie notices about the string in her bubbles experiment.

RESUME video.
PAUSE video after Stephanie says, "Hmmm."

TEACHER: What did Stephanie notice? (The string was pulled into a round shape, and bubbles are round.) OBJECTIVE 6. Todd and Hopey are visiting chemist David Katz. Listen and watch to be able to share the three ingredients of the bubble solution that David gives to Todd and Hopey.

RESUME video.
PAUSE video after David says, "too long for the solution to settle down."

TEACHER: What were the three ingredients in the recipe? (Water, soap, glycerin.) Which of the ingredients seems unusual to you? (Glycerin.) Listen to the reason you add glycerin or corn syrup to a bubble solution, plus be able to identify the layers of a bubble.

RESUME video.

STOP video after David says, "The bubble lasts longer."

TEACHER: Turn to your neighbor and describe what the layers of a bubble are. Then your neighbor is to tell you what the glycerin does for the bubble. (Bubble layers are soap, water, soap. Glycerin makes the water layer thicker so the bubbles last longer.) OBJECTIVE 7 & 8.
GRADES K-2: Bubble Shapes
You may want to spread newspapers on the floor before starting this activity. Distribute odd-shaped bubble tools (or have students make close-shaped tools from pipe cleaners) and a container of bubble solution to groups of about 4 students. Ask students to predict the shape of the bubbles from their tools. Record this information on a class chart. OBJECTIVE 4. After the students have made predictions, allow them some time to experiment with various bubble tools.

NOTE: Caution them not to stir up the solution to make foam, because it will not make good bubbles that way.

When the students have had reasonable time to experiment with the tools, ask them to describe the bubble shapes they created. OBJECTIVE 5. When they tell you that all of them are round, ask someone to tell the class the name of a force that causes that to happen. They should be able to tell you surface tension. If you would like to do an additional activity with bubbles, direct students to make bubble frames. These are made of 2 plastic straws, or one cut in half, and about 30 cm of string (15 for half straws). To draw the string through the straws, simply put the end of the string in the straw and suck gently on the other end.

NOTE: The teacher may want to take care of this preparation. But, if you have students do this, warn them to suck gently, or the string will come through too fast and go down their throat.

When the string is through both straws, tie the ends together and hold the frame by the straws to blow large bubbles. For obvious reasons, this activity is better accomplished outside, if possible.

GRADES 3-6: Table Bubbles
Part 1:
Direct students to clear their desks of all objects and to cover the floor around their desks with newspaper. Distribute a small plastic cup, 3 to 5 oz. of bubble solution and a plastic drinking straw to each student. Tell the students that they are going to be making some large bubbles on their desks. To do this they will need to pour a small amount of the solution on their desks and spread it around. The teacher demonstrates the appropriate small amount. If the bubble touches a dry spot it is likely to pop. When they have their desk wet they are to dip their straw into the cup of solution and put it down on the wet spot and blow gently. It may take them a few tries to begin to make bubbles; most often they will blow too hard. Once they are successful with the bubbles, direct them to make the largest bubble they can. They will learn that they can even take the straw out of the bubble and put it back in as long as the straw is wet. When the bubbles pop, they will leave a ring marking the size of the bubble. Students measure the diameter of the ring with a plastic ruler to determine the size of their bubbles. The teacher records the sizes on the chalkboard, as student desks will be too wet to record there. OBJECTIVE 9.

Part 2
Directions for Bubble Collars
For each pair of students: 1 sheet of white paper 12" by 18". Cut the sheet in half, length ways, for 2 pieces that measure 6" by 18". These can be laminated to last longer, but it is not necessary. Staple the two pieces together to make a strip 6" by 35" and then staple the 6" ends to form a ring.

When the students have had time to experiment with bubbles on their table tops, pass out the bubble collars (older students may be able to make the collars themselves), one for each pair of students. The students take turns blowing bubbles and placing the collars over them.

Eventually, the students are to blow a large bubble and place the white bubble collar around it. The purpose is to observe the colors and patterns of the bubble until it pops. After they have experimented with making several bubbles, instruct them to observe the pattern of the bubble solution again, and this time predict when the bubble will pop. With careful observation and discovery of "a particular bubble behavior," the students will become very accurate. OBJECTIVE 10.

ASSESSMENT: Based on the information about surface tension and bubble layers from the lesson, students are to write their interpretations of the discoveries on bubble behavior, including when they may pop.

NOTE: To facilitate clean-up, do not let students try to clean their desks with damp sponges or paper towels; this will make lots and lots of suds! Put some vinegar into a spray bottle and spray vinegar on each desk. Then use the squeegee and scrape the liquid into a plastic container or pail. Following this, the students may wipe their desks with sponges or paper towels. Great for cleaning desks!
• Invite a chemistry teacher to talk about various bubble solutions. Students should have questions prepared in advance.

• Write letters to several soap manufacturers asking how their product works. Ask why it was invented.
• Art:
Add liquid soap to tempera paint, and put the solution into a shallow pan such as a tin pie plate. Students blow bubbles in the solution with a plastic straw and gently lay a piece of paper on the bubbles. Bubble outlines will be left on the paper. Follow this procedure several times, using several colors, and your results will be interesting designs.

Poetry:
Students write haiku or other forms of poetry inspired by their bubble creations.

Science:
Additional surface tension activities include:
1. Students make drops of water on a piece of wax paper to observe the dome shape.

2. Float an empty berry basket on top of water in a container. Even with the holes in it, it will float. Students explain why. (ASSESSMENT.)

3. Place a clear glass or plastic container on the overhead projector, and sprinkle a little black pepper on the water; it will float. Put a little liquid soap on your finger and touch the pepper-covered water. The surface tension will break where the soap touches it and pull the pepper away. Students explain why. (ASSESSMENT.)

4. Students design an experiment to determine which brand of soap makes the largest bubbles, longest-lasting bubbles, etc.

5. Questions for student research:
What is glycerin?
What other uses does glycerin have besides bubble making?
What are the positive and negative aspects of surface tension?
How does surface tension in space react? Does it change?
How are bubbles blown in space?
What does soap do to dish water?
What is hard water, and soft water? Does this affect surface tension?
What does lye do to hard water?
How do things float on top of water?

RESOURCES
1. Project AIMS, "Soap Films and Bubbles"
2. Lawrence Hall of Science GEMS, "Bubble Festival"
3. Other ITV courses on this topic from ASSET (Here's How #20 "Soap Making")

### Master Teacher: Ann Parra

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