• Before class make copies of the following handouts in the form most appropriate for each of your students:

1. Student Activity, “The Spongy Universe'
2. Student Text, “The Spongy Universe” Part One
3. Student Text, “The Spongy Universe” Part Two
4. Reporting Sheet for observations and inferences

• Use the template for the Spongy Universe Tactile Cards #1 - #5 to make braille and/or thermally-enhanced copies. For instructions see the materials section above.
• Preview the text material using your audio-amplified computer software and in Braille. Give your sight-impaired students any instructions they need to take advantage of their appropriate learning aids.

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Procedure

Use the following warm-up activity so that students become familiar with the scientific observation vs. explanation (inference) process they will be using the Part One of the student activity.

Inference Activity

1. Introduce the activity with the following instructions:

This activity is designed to help you learn to formulate explanations or inferences. Every inference must be drawn from an observation, so you will first be making careful observations and then interpreting or explaining them. Your interpretations or explanations are inferences.

2. Distribute copies of Tactile Card #1 in the appropriate format to each student.

Tactile Card 1

• What do you think this might be? What might be happening?
• What do you see in position 1? In position 2? In position 3?
• What is happening to the spacing between footprints as you go from position 1 to position 2?
• Were the big bird and the little bird in position 2 at the same time?
• Do we know that both birds were there at the same time in any of the positions?
• Do we know WHEN the birds came?

Whether they are doing this activity in writing or verbally, have students make at least two observations about each frame.

4. Have students complete the following table individually or as a whole class activity in the format(s) most appropriate for your students. Have them write or express verbally at least one inference that could be drawn from that observation. (More than one inference can be drawn from any single observation.) You could also divide the class into smaller groups and then compile their responses in a follow-up class session. Have them compare their answers with those of their classmates. How are the responses similar? How are they different?
   

5. Explain to the students that, as they were doing this activity, they were acting like scientists who make observations that they must then explain. There are often many different explanations for the same set of observations, so it becomes the job of scientists to determine which of the explanations is the most likely. When explanations don’t all work, we have to test the explanations.
   
   
6. Have students evaluate the possibilities that they listed by asking:

• Which possibility do they think is the most likely explanation?
• On what basis do they think the decision about the most likely possibility explanation should be made?
• What other information might be useful in determining which possibility is most likely the correct one?
• How might they go about obtaining this additional information?

  Use this graphic as an analogy of what happens when we observe something happening in space. We observe space as it is now but we don’t know when it happened. We don’t have instruments to see all things in space, just what is happening in small regions in space.

7. Ask students whether or not we can we make any firm inferences about the “tracks in the snow” graphic? All we really know is that only that one bird walked away in position 3.
   
   
8. Explain to students that just as they made observations and inferences of the tracks, they will now be doing the same thing with an ordinary sponge.

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9. Distribute sponges and copies of the Student Activity “The Spongy Universe” in the form(s) most appropriate for your students. (See the “Materials” section above for options for using tactile examples of objects mentioned in the text.) Select from the following list the most appropriate procedure for your students as they complete Part One of the Student Activity.

• Complete the activity as a group, sharing observations and answering questions verbally.
• Have students complete the activity in pairs, and record observations and answers to questions either on print copies or in Braille.
• Have students complete the activity individually and record observations in the most appropriate way.

10. Whichever method you select for Part One:

• In Step One, instruct your students to describe the structural details of the sponge as being large or small, deep or shallow, regular or irregular shapes, smooth or textured. You may want them to estimate sizes in centimeters. The possible student observations will depend upon the type of sponge being used.
• In Step Two, students’ verbal or written descriptions of the process they think was used to create the sponge should be logical and/or creative, depending upon the final outcome that you desire for your students.

Possible answers to Step Two might include:

• The material that forms the solid was a liquid that was poured over objects which were removed after the solid had cooled.
• The solid was formed by different substances that formed gas bubbles as the sponge was being made. The gases escaped after the sponge was formed.
• The solid material was squeezed out in strands; the strands then joined leaving holes between them.
• A gas was blown into the solid as the sponge was being formed.
• Sponges are the remains of an organism after partial decay.
• It was heated in a microwave and it exploded.
• It was made of two kinds of material and it separated.

11. After students have completed Step Two, distribute copies of the Student Text, “The Spongy Universe” Part One, in the appropriate forms. Tell students that you have labeled samples of Swiss cheese, a bead necklace, a chain, string or fish-line filament, and a piece of lace for them to observe as they read the text.
    
    
12. When all students have read the Student Text, “The Spongy Universe” Part One, bring them together for a feedback session to discuss their answers to the questions in Step Three of the student activity:

• When do you think that the “Hubble bubbles” formed—early in the formation of the universe or late in the history of the universe? Why do you think this?
• What do you think caused the formation of the “Hubble bubbles”? What information or observation led you to this conclusion?
• Do you think that there is anything in those "voids" that we cannot see? Why or why not?

• There are two models that you could use to help students understand how bubbles might have formed early in the universe. One of them involves the baking of a cake. The baking powder or baking soda causes a chemical reaction to take place, producing gas bubbles as the batter is baking. [The baking process might be analogous to early universe, which is thought to have been much hotter than it is now.] If the cake is removed from the oven and carefully placed on a surface to cool, the bubbles stay intact.
• The other analogy is a description of how Swiss cheese is formed. Cheese is made from a liquid mixture of dairy products. The action of bacteria in the cheese produces bubbles of methane, which are trapped as the solid cheese is formed.
• You can use an inflated balloon to model for the formation of the Hubble bubbles later in the universe development. Rub the balloon on a piece of cloth to create static electricity that will attract pieces of paper. This models how solid particles could have gathered on the surface of the bubbles. If you are using a plastic balloon, you may wish to attach some tacky tack to the side of the balloon for students to observe.
• Use Tactile Card #2 to illustrate that we can see stars through the Hubble bubbles. Tactile Card Two is based on the Hubble Bubble images at:
  http://www.apo.nmsu.edu/site/directory/ebergeron/snoopy/bubble.html
  You may wish to access this site for the use of your partially-sighted students. The images show three Hubble Bubbles, one of which is elliptical (Hubble II) and another (Hubble III) that is a thin spherical shell of uniformly expanding gas with pockets of gas expanding independently on the surface of the shell.

• Have them compare these graphics to the bubbles they observed in sponges.
  

1. Have available the sponges that students used in part one of the activity and Tactile Cards #3, #4, and #5.
   
   
2. Introduce this part of the “Spongy Universe” activity with wording something like this:

“When you felt your sponge in the first part of the activity, you probably noticed how large it is. Feel it again and estimate how large it is.”

Hand out the sponges and let students estimate the size. If they give you the dimensions in inches, you may want to remind them that scientists use the metric system.

3. Hand students copies of Tactile Card #3. Tell them that the raised figure on the card is a model of the real sponge. Have them feel the raised sections of the model that represent the solid parts of the sponge. The depressed areas of the model represent the holes in the real sponge.

   Ask them how the dimensions of the real sponge compare to the dimensions of model. When they are next to each other they should be about the same size.

4. Now ask if anyone has counted steps from the end of the hallway to the classroom. [Some of them probably have, since this is a technique used by many blind and partially-sighted persons in a familiar environment.] Ask them what they think would happen to the size of a real sponge if someone carried it down the hallway as far as he could go. Would the size of the real sponge change? [No] Would the sponge appear to be the same size if it were that far away from you? [If you have students with some sight, have someone actually
   carry the sponge down the hall so that partially-sighted students can experience the fact that the sponge appears to be smaller. You may wish to have the person carrying the sponge count his steps as he carries the sponge down the hall. That way they can hear his voice getting farther away and, if any of them count steps as they move from place to place, this will give them a point of reference. Your partially-sighted students can then tell their blind classmates what they see. Otherwise you should do this.]

   Hand students copies of Tactile Card #4. Tell them to estimate the size of this sponge model. Is it the same size as the real sponge? Have them feel the size of the holes in this sponge model. Are they the same size as they are in the real sponge? Tell them that this is the size that the sponge appears to be when it is viewed from the distance in the hallway. The size of the sponge has not changed. Only the distance between the sponge and viewer has changed.

5. Ask students how large they think the real sponge would appear to be if someone were holding it out in the parking lot. Hand students copies of Tactile Card #5 and tell them that the real sponge might appear to be about this size if it was in the parking lot and we were viewing it from the classroom. Ask them what has happened to the size? Is it smaller or larger than the real sponge? Is it smaller or larger than it appeared to be at the end of the hallway? Can they feel the holes in the model in Tactile Card #5 as distinctly as they could in the real sponge or in Tactile Card #3? Ask students how large a real sponge might appear if it were in space? Do they think that they could see the holes in the sponge? Again, lead them to the conclusion that objects in space appear to be very small and that scientists cannot easily observe the details of those objects.
   
   
6. Continue using wording similar to the following:
   How close or far away from an object we are makes a dramatic difference on how much detail we can learn about the object or objects we are interested in. When we look out into space, the amount of information obtained depends on
   how small or large a section of space we are observing, how far away an object is located, and what type of instrument we are observing the objects with. For instance, we could use binoculars, Earth bound optical telescopes, the Hubble Space Telescope, infrared telescopes, spectro-analysis equipment, or a radio telescope.
   
   
   
   Each of these gives us different information about the same object. To give you an idea how information obtained about the same object using different instruments can be different we will look at a sponge using your White Cane and a pencil. Their canes will model using a “long-range” telescope and the pencil models using a pair of binoculars.
   
7. Identify an area that is no larger than six feet by eight feet to be the area in space that the students will search for a galaxy (a sponge). You or a partially-sighted student should use masking tape to secure a sponge on the floor somewhere in that area. The searching student is a “searching scientist.” Tell the searching scientist to use sweeping motion of his/her cane to locate the spongy galaxy. Have a sighted student time how long it takes the “searching
   scientist” to find the sponge.

   Now repeat finding the sponge, taped to a different spot, using a pencil. Again have a student time how long it takes.
   [You may wish to caution students taping the sponge not to make any noise during the taping. Students observing this activity should also be told not to make any sound that might indicate how closely the searching student is to the sponge.]

   As time permits, give as many students as possible the experience of locating a sponge using a “long range” telescope (white canes) and “binoculars” (a pencil). Partially sighted students should be blind-folded if they are the “searching scientists.”

   To make this a more scientific study, have some students use the cane first and other students use the pencil first. See the text box for actual results during pilot testing.

8. Place sponges on the table in the classroom and have students use their folded canes to feel the features of the sponge. Ask them what information they can learn about the sponge’s features. Have them repeat exploring the sponge, using a pencil. [They should not use their fingers.] Again, ask what information they could observe from the pencil examination. Have them compare and contrast the information obtained by each instrument. What are the advantages and disadvantages of each in searching and finding the sponge in the universe and the type of information obtainable from the examination of the sponge?

Ask students to think about finding their way around the school building or the Solar System and around the school campus or the Universe using only a pencil. Even our best instruments today are only pencils when it comes to the vastness of space. Now ask them if they can understand why new discoveries in space are not made everyday.

9. Distribute copies of the Student Text, “The Spongy Universe” Part Two in the appropriate form(s). Students should read this text before engaging in the following class discussion.
   
   
10. Start the feedback class discussion with questions similar to the following.

• Is a sponge a good model of a homogeneous and isotropic universe? Why or why not?

  Possible student “why not” answers include the fact that sponges are squeezable and that they soak up liquids. Whether the students mention these characteristics or not, you might want to mention that a “compressed sponge” might be a model for the early universe, and as you release it, not only the whole sponge expands, but so do the “voids.” If you are planning to continue with other activities in this module, you might want to tell students that they will continue to work with sponges later in the module.]

• After reading the Student Text, "A Spongy Universe," do you think that the universe is isotropic and homogeneous? Why or why not?

• What further information or observations would you need to make before you could form a better answer to this question?
  

1. To expand the concept of the cosmic structure to include the differing densities of the structures, give students a box containing different types of materials, such as marbles, cotton balls, wooden blocks, balloons, and packing peanuts. After allowing them to examine the different items:

• Ask them whether or not this would be a better model for structures of the universe than a sponge? Why or why not?
• Point out the difference in the density of the different items in the box. Ask whether they think that the different structures in the universe have different densities.
• Would it be easier or more difficult to explain how these structures were formed than it was to explain how the sponge was formed?

2. To relate this activity more directly to the National Science Education Science and Technology and History and Nature of Science Standards, distribute copies of Appendix C, "Selected Noteworthy Events in Cosmology" in the appropriate format. Discuss some or all of the questions posed in the Background Information at the top of the Teacher Guide.

1. Coming of Age in the Milky Way, Timothy Ferris, William Morris and Company, Inc., New York, 1988.

2. Bright Galaxies, Dark Matters, Vera Rubin, American Institute of Physics Press, Woodbury, NY, 1997.

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Resources and Reference

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