session 1.5 mystery of the floating balloons sapaytan...session 1.5 mystery of the floating balloons...

Unit Goalsscience content• The Ocean as a Heat Reservoir• Density and Movement of

Ocean and Air Currents• Water Cycle

practices of science• Making explanations from

evidence• Using models

natUre of science• Scientific explanations are based

on evidence• Technology plays a role in

gathering new evidence

science lanGUaGe• Using science vocabulary• Having evidence-based

discussions

52 • Ocean Sciences Sequence 6–8

Session 1.5

Mystery of the Floating Balloons

Students begin by watching the teacher take four different-colored balloons, each filled with a different mystery substance, and place them in a container of water. Students observe that some sink and some float. To solve the

mystery of what happened with the teacher’s balloons, groups of four students investigate by filling their own balloons with water at various temperatures and salinity levels to test for sinking or floating. The concept of density is introduced in this session, and students may begin to apply it to the mystery. Students will have many more opportunities to explore and understand density in the next few sessions. Student learning is focused on the following key concepts:

• For any one type of substance, such as water, it will be denser if the molecules are closer together. It will be less dense if the molecules are farther apart.

Students also learn:

• Density is a measure of how tightly packed molecules are in a substance or in a solution.

mystery of the Floating balloons Estimated Time

Introducing Density Using Molecule Cards 10 minutes

Introducing Floating Balloons Mystery 10 minutes

Investigating to Solve the Mystery 20 minutes

Discussing Group Results and Mystery Balloons 5 minutes

Total 45 minutes

Ocean Literacy Scope and Sequence and Climate Literacy principle Correlations Ocean Literacy S&S 1.B.4. Ocean water gets denser as salinity increases and as temperature decreases.Climate Literacy Principle 5.A. Our understanding of the climate system is improved through observations, theoretical studies, and modeling.

Unit 1 • 53

What You Need

LANGUAGE OF SCIENCEvOCAbULARyabsorbatmosphereclimatecondense/condensationcurrentsdense/densityevaporate/evaporationevidenceheat energyheat reservoirmattermodelmoleculeprecipitationwater cyclewater vapor

LANGUAGE OF ARGUmENTATIONWhat do you think?Why do you think that?What is your evidence?Do you agree? Why?Do you disagree? Why?How sure are we?How could we be more sure?

Session 1.5

Mystery of the Floating Balloons

❏ Investigation Notebook: optional page 24 (DWR) ❏ (optional) Copymaster Packet: Solving a Floating Balloons Mystery

*not provided in kit

GETTING READybefore the day of the session: 1. Set up projection system/review multimedia. Set up and test the projection

system to be sure all students will be able to see items projected during the session. Spend a few minutes reviewing this session’s materials and supplemental resources found at mare.lawrencehallofscience.org/oss68 or by following the links (eBook) or using the resource disc (print version).

2. prepare ice balloon. Set aside four different-colored balloons for the teacher demonstration. Fill one of these four demonstration balloons with water, making sure there is no air inside. Pour water into it using a funnel and a cup until it is about 1½"–1¾" across. Place the filled balloon in a bowl so it keeps its round shape, and place it in a freezer. Keep the ice balloon frozen until you begin the demonstration. When you prepare the other three demonstration balloons, just before the session begins, make them the same size—1½"–1¾" across.

3. Obtain or make ice. You will need a bag of ice or an equivalent amount in ice cubes. Use a freezer or an ice chest to keep the ice cold in your classroom.

4. prepare trays. For each group, place the following materials on a tray (see Figure 1–5 on page 54):

_ 3 balloons (label “1,” “2,” and “3” with a permanent marker)5. Copy student sheets. Make copies of the following from the Copymaster

Packet: _ Molecule Cards (one sheet for each pair of students) Cut apart the six cards and clip each set together with a paper clip.

_ Balloon Investigation Data Sheet (one for each group) _ Balloon Investigation Directions (one for each group) Attach 3 sticky notes.

6. make charts. Using a marker and chart paper, make the following charts: _ Floating Balloons Mystery Demonstration (See Figure 1–6 on page 59. Write only the title and draw the tank without the balloons.)

(continued on next page)

❏ 1 clear plastic container (5 gallon) ❏ 4 balloons, each a different color (for

teacher demonstration) ❏ water* ❏ cereal-size bowl* ❏ 3 dishpans ❏ electric kettle* or hot tap water* ❏ 1 bag of ice* ❏ cooler or ice chest* ❏ 1 heaping teaspoon of salt

❏ 2 sheets of chart paper ❏ 4 colored markers (to match teacher

balloon colors)* ❏ 1 permanent marker ❏ masking tape ❏ projection system* ❏ computer with Internet connection*

or resource disc ❏ 5 slides for Session 1.5 ❏ Copymaster Packet

❏ 2 sets of Molecule Cards ❏ 2 paper clips* ❏ 1 cafeteria-style tray ❏ 1 teaspoon ❏ 1 funnel ❏ ¼ cup of salt (4 Tablespoons)

❏ 1 clear plastic cup (9 oz) ❏ 1 paper cup (8 oz) ❏ 3 balloons (all same color) ❏ 1 tank (1.5 gallon) ❏ 3 sticky notes ❏ 1 Data sheet and 1 Direction sheet

For each group of students:

For the class:

Next Generation Science Standards (NGSS) Correlations Available online: www.mare.lawrencehallofscience.org/oss68

For each student:

_ 1 spoon _ 1 funnel

_ ¼ cup of salt in a 9 oz plastic cup _ 1 paper cup


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Student Sheet—Ocean Sciences Sequence 1.5, 1.6

Balloon Investigation Data Sheet

Decide what to put in each balloon. Predict what will happen when you place the filled balloon in

a tank of slightly warm water. Record the type of water and your prediction, as well as evidence for

your prediction, in the table. Once the first two columns are filled in, test the balloon. Then, record

your results, both in the table and in the diagram below.

Group Members _____________________________________________________________

_____________________________________________________________________________

SUBSTANCE

What will you put

in the balloon?

PREDICTION

Do you think the balloon will sink, fl oat,

or go between? Why do you think that?

RESULT

What happened?

Where did the balloon go?

Balloon #1:

Balloon #2:

Balloon #3:

Diagram of Results

Draw where in the tank each balloon went. Label the balloons “1,” “2,” and “3.”

SESSION 1.5 mySTERy OF THE FLOATING bALLOONS

Figure 1–5. Set up materials for each group on a separate tray for ease of distribution.

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Student Sheet—Ocean Sciences Sequence 1.5

Balloon Investigation Directions1. Start with balloon #1. Choose a substance to put in your balloon:

(1) hot water, (2) cold water, or (3) room-temperature water. Another option is to add

salt to any of the three types of water.2. Record your substance and your group’s prediction on the data sheet. How will the

water-filled balloon respond when you place it in your test tank? Sink to the bottom,

float on the surface, or go somewhere between?3. Use your group’s paper cup to get your chosen water from the labeled containers, and

bring the cup and water back to your group.4. If adding salt, stir 1 spoon of salt into your cup of water, before adding the water to the

balloon. 5. Work over the tray. Using the funnel, pour the water into the balloon until it just

overflows, pinch the balloon near the opening and squeeze just a little water out of the

balloon to make sure there is no air inside, and then tie off the balloon.

6. Place the balloon in the test tank. After 30 seconds, record where the balloon ends up,

and draw it on the tank diagram on your data sheet. Write why you think the balloon

responded in that way. Indicate with arrows if the position of the balloon changes as

you are doing the investigation. Put the balloon number on your drawing.

7. Use a sticky note to add your group’s results to the class chart, Balloon Investigation

Results. First write what substance was in the balloon, then position the sticky note so

it shows where your balloon was located about 30 seconds after you added it to your

tank.

8. Repeat steps 1–7 with your next substance and balloon, or until your teacher announces

it is time to clean up.

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Group Members _____________________________________________________________

_____________________________________________________________________________

SUBSTANCEWhat will you put in the balloon?

PREDICTION

Do you think the balloon will sink, fl oat,

or go between? Why do you think that? RESULTWhat happened?


Balloon #1:

Balloon #2:

Balloon #3:

Diagram of Results


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Unit 1 • 55

GETTING READy (continued)



_ Balloon Investigation Results (See Figure 1–7 on page 63. Write only the title and draw the tank without the sticky notes.) Post the chart where students can access it easily to record their results.

Immediately before the session:1. Set up water stations. Using dishpans, set up three water stations so each is

accessible to several students at once. Label each dishpan with the temperature of water it contains. _ Cold water. Place water and ice in one dishpan. Use enough ice so the water is very cold, but there should still be plenty of liquid water.

_ Hot water. Place very hot tap water or water heated in an electric kettle in another dishpan. This water should feel hot to the touch, but not burn.

_ Room-temperature water. Fill another dishpan with tap water and let it come to room temperature, approximately 22°C.

2. Fill test containers. Fill the clear 5-gallon container (for teacher demo) with tepid tap water (about 34°C). Label it “slightly warm freshwater.” Add warm tap water (about 34°C) to the group tanks until the water is about 5" deep (almost to the top of the tanks).

3. prepare remaining teacher-demo balloons. Do not let students see what you are putting into these balloons. Use a funnel (or turkey baster) to fill the balloons with water from the water station dishpans, just as your students will do. Be sure the balloons are all about the same size (no larger than 1½–1¾" across). Important: tie off the balloons, making sure no air is inside. _ Cold-water balloon. Fill with water from the cold water station. Place the balloon into the cold-water dishpan to stay or to become very cold.

_ Hot-water balloon. Fill with water from the hot water station. Place the balloon back into the hot-water dishpan to stay hot.

_ Salty balloon. Fill a cup about ⅓ full of room-temperature water (about 22°C) from the room-temperature water station and add about one heaping teaspoon of salt. Mix it up and pour into the balloon.

4. Gather the four teacher-demo balloons. Just before the session begins, get the ice balloon out of the freezer, and bring the other three balloons (cold, hot, and salty) near the 5-gallon teacher-demo water container.


SESSION TITLE HERE OkSESSION 1.XXSESSION 1.5 mySTERy OF THE FLOATING bALLOONS

Introducing Density Using molecule Cards 1. Water vs. air molecules. Remind students that all substances,

including water and air, are made of molecules. Have students think back to the simulation showing molecules in bottles of water vs. air. Ask, “Which molecules are farther apart from one another—water molecules or air molecules?” [Air molecules are much farther apart from one another than water molecules, even when both are at the same temperature.]

2. Introduce Molecule Cards. Tell students that each pair will get a set of Molecule Cards. These cards are a model used to represent a sample of air or water molecules in a capped bottle like students were using in the Water vs. Air activity. Pairs will decide which card they think might represent molecules of water and which might represent molecules of air. Distribute a set of Molecule Cards to each pair of students. Remind them to discuss their reasoning.

3. Partners share ideas with whole group. After a few moments, ask each pair of students to hold up a molecule card that they think represents molecules in water. Then have them hold up a card they think represents molecules in air. Each time, ask students to look around the room at which cards other students are holding up.

4. Explain that there is no one right answer. Pairs may have chosen different cards. Tell students there are many right answers. Whichever two cards they chose, the card representing water molecules should have closer-together molecules than the card representing air molecules.

5. Project slide; introduce guiding question; Project the slide with the new guiding question, and have students read it aloud.

6. Introduce the word density. Tell students that density is the word for how dense a substance is. Density is a measure of how tightly packed molecules are in a substance or in a solution, such as salt water. Tell students that they will be learning more about density of water and air in this session and throughout the unit.

7. Project slide; students record key concept. Project the slide with the key concept, and have students read it aloud. Then have students turn to page 6, Key Concepts, in their Investigation Notebooks and copy the key concept on the lines below Guiding Question #3. Collect the Molecule Cards and save them to use again in later sessions.

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Name __________________________________________ Date _________________________


Molecule Cards

Student Sheet

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6

Key Concepts (continued)

Guiding Question #2: How does the ocean affect climate on Earth?

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

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______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Guiding Question #3: What is density?

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Student Sheet—Ocean Sciences Sequence 1.1–1.12

Investigation Notebook, p. 6

Unit 1 • 57

TEACHER ConsidERATions



DAILy wRITTEN REFLECTIONwhat did you discover about molecules and heat energy from the simulations and activities that we have done so far? This prompt, found on page 24 of the Investigation Notebook, asks students to think about their observations and the previous activities about molecules and heat energy. Thinking about this will help prepare students to delve deeper into the topic of density in this session.

SCIENCE NOTESAbout Substances Not made of molecules. Some substances, such as pure metals, are made of single atoms not bonded together into molecules, so it is not entirely accurate to say that all substances are made of molecules. It is fine for the purposes of this unit to not be completely accurate about this, as students will learn more about atoms and molecules later.

INSTRUCTIONAL ROUTINEmolecule Cards. Students will use the Molecule Cards introduced in this session throughout the unit. They serve as visuals to help students discuss density. Students’ reasons for choosing particular cards to represent air or water molecules are more important than which cards they choose. The following information is not meant to be shared with your students at this time. The two cards with the fewest molecules represent gases. The card showing two types of molecules represents a solution, such as salt water. The other three cards represent water molecules at different temperatures.

INSTRUCTIONAL RATIONALEwhy we Introduce Density This way. In this unit, students learn about density as they engage in investigations and discussions about molecular spacing, thereby encouraging them to test their ideas and providing them with a solid grounding and applied understanding of this often difficult-to-understand concept. If your students are more experienced, you might also want to introduce the formula, but we suggest you do so only after they have had the opportunity to be immersed in experiences with density.

ASSESSmENTQuick Check for Understanding: pairs Explore molecule Cards. As pairs discuss the Molecule Cards to decide which ones represent water and air, listen in to their reasons. They should refer to the two heated bottles (water vs. air) and the discussion that water contained more matter (molecules) than the same size bottle of air.



Introducing Floating balloons mystery1. Introduce demonstration of floating balloons. Tell students that

you filled four balloons with different kinds of water, and you will now place each filled balloon into a large, clear container of slightly warm freshwater. Point out the label. Remind students that the term freshwater is another way to describe water without salt. Tell students that you will record the results by drawing where each of the four balloons ends up in the tank on the Floating Balloons Mystery Demonstration chart (see Figure 1–6).

2. Place balloons in water container. One at a time, place the balloons into the container as students observe carefully. (Don’t let students see where you are taking the balloons from, or let them touch the balloons, as it will give away the mystery.) About 30 seconds after each balloon is placed, record the results on the Floating Balloons Mystery Demonstration chart by sketching the balloon in its position in the tank and either labeling it by the color of the balloon, or using a colored marker. Have students help you accurately record the relative positions of the balloons in the tank, e.g. two balloons may be floating at or near the surface, but one may be floating a little higher than the other and so should be shown on the chart as floating a little higher.

3. Look at position of balloons again. Have students continue to watch the tank for a few minutes to observe any changes. [Within a couple of minutes, the cold-water balloon will start to rise slowly in the tank.]

4. Turn and Talk. Have students Turn and Talk to their partners about what they think is different about the water in each balloon, based on whether the balloons floated or sank and their positions in the tank relative to each other over time.

5. Announce that students will investigate. Tell students that you aren’t going to give them the answer as to what kind of water was in each of the balloons; instead, they are going to gather evidence by doing some balloon investigations. They will try to make their balloons behave like your balloons did.

Investigating to Solve the mystery 1. Explain procedure. Explain that each group of four students will

start by deciding on one kind of water to try in a balloon and predict whether it will sink or float in a tank of slightly warm freshwater. They will have the choice of (1) cold freshwater, (2) hot freshwater, or (3) room-temperature freshwater. They may add salt to any (or all) of these temperatures of freshwater if they predict it will make the balloons behave like the balloons did in the demonstration.


Unit 1 • 59




INSTRUCTIONAL RATIONALEExpectations for Understanding Density. This is the first time in the unit that the word density has been formally introduced. Depending on the experience of your students, this may be the first time they are hearing a scientific explanation of the concept. Be assured that it isn’t necessary for students to have a complete understanding of density at this point. Students will investigate various aspects of density throughout the rest of the unit. Students will gain experience with the movement of molecules and how tightly packed they are at different densities. They will eventually be introduced to how differences in density set the atmosphere and ocean currents in motion.

INSTRUCTIONAL SUGGESTIONSDon’t Reveal the Content of the balloons. It is important not to tell the students what is in each demonstration balloon until the next session. Be careful not to let students see where you are taking the balloons from, or let them touch the balloons. This way, students are encouraged to use their experimental evidence to figure out what is in the mystery balloons.

what Some Teachers Did: Individual Students Complete Data Charts. Rather than having small groups complete the Balloon Investigation Data Sheet, you may want individual students to record results on their own data sheets, in which case you would need to make one copy of the Balloon Investigation Data Sheet (in the Copymaster Packet) for each student.

Floating Balloons Mystery

Demonstration

red

blue

yelloworange

Figure 1–6. Students will compare the results of their investigations to this chart.



2. Students will test one substance at a time. After filling a balloon and testing it in a tank, group members will watch it for about 30 seconds and record whether it sank or floated or something in between. The group may then try a different water in another balloon. The point is not to try just anything, but to test things that they think might have been in the balloons shown in the demonstration. If they can get a balloon to behave like one of those balloons, that could be evidence about what was in the balloon in the tank.

3. Point out water stations. Show students where the labeled cold, hot, and room-temperature water stations are located. Tell them that if they decide to use salty water, they can add one spoon of salt to about 1/3 cup of water, and then pour that water into their balloons. Emphasize that they should mix the salt and water together first, and then add it to the balloon, rather than putting salt directly into the balloon.

4. Show group materials. Each group will have a direction sheet, a test tank with slightly warm freshwater, a spoon, a funnel, three balloons, and a cup of salt. Caution students not to mix anything into the water in their tanks.

5. Project slide; pass out student data and directions sheets. Display the first Balloon Investigation Directions slide and pass one Balloon Investigation Data Sheet and one Balloon Investigation Directions sheet to each group. As you refer to the slide, use an example to explain how groups will complete the sheet.

• If a group decides to put cold water in a balloon, they will write “cold water” in the Substance column.

• Next to that, they would write “float,” “sink,” or “between” in the Prediction column, along with their reasoning supported by evidence for making such a prediction.

6. Project slide; demonstrate balloon-filling procedure. Show groups how to use the paper cup on their trays to obtain water from one of the water stations. They will bring the water back to their own tables to fill the balloons. Model how to fill a balloon using a cup and funnel with the tray underneath to catch any spills. Explain that they need to make sure there is no air in any of the balloons because air will make the balloons float no matter what kind of water is in the balloon. To get the air out, they can fill a balloon to the very top with water, then squeeze a little bit of water out as they pinch the neck of the balloon completely, and then tie off the opening of the balloon. Emphasize how important it is to get all the air out. Remind students that they will try only one type of water in a balloon, and only one balloon at a time.

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Balloon Investigation Directions

1. Start with balloon #1. Choose a substance to put in your balloon: (1) hot water, (2) cold water, or (3) room-temperature water. Another option is to add salt to any of the three types of water.

2. Record your substance and your group’s prediction on the data sheet. How will the water-filled balloon respond when you place it in your test tank? Sink to the bottom, float on the surface, or go somewhere between?

3. Use your group’s paper cup to get your chosen water from the labeled containers, and bring the cup and water back to your group.

4. If adding salt, stir 1 spoon of salt into your cup of water, before adding the water to the balloon.

5. Work over the tray. Using the funnel, pour the water into the balloon until it just overflows, pinch the balloon near the opening and squeeze just a little water out of the balloon to make sure there is no air inside, and then tie off the balloon.

6. Place the balloon in the test tank. After 30 seconds, record where the balloon ends up, and draw it on the tank diagram on your data sheet. Write why you think the balloon responded in that way. Indicate with arrows if the position of the balloon changes as you are doing the investigation. Put the balloon number on your drawing.

7. Use a sticky note to add your group’s results to the class chart, Balloon Investigation Results. First write what substance was in the balloon, then position the sticky note so it shows where your balloon was located about 30 seconds after you added it to your tank.

8. Repeat steps 1–7 with your next substance and balloon, or until your teacher announces it is time to clean up.

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Group Members _____________________________________________________________

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SUBSTANCEWhat will you put in the balloon? PREDICTIONDo you think the balloon will sink, fl oat,

or go between? Why do you think that?RESULTWhat happened?


Balloon #1:

Balloon #2:

Balloon #3:

Diagram of Results


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Balloon Investigation Data SheetDecide what to put in each balloon. Predict what will happen when you place the filled balloon in a tank of slightly warm water. Record the type of water and your prediction, as well as evidence for your prediction, in the table. Once the first two columns are filled in, test the balloon. Then, record your results, both in the table and in the diagram below.

Group Members _____________________________________________________________

_____________________________________________________________________________


PREDICTIONDo you think the balloon will sink, fl oat, or go between? Why do you think that?

RESULTWhat happened?


Balloon #1:

Balloon #2:

Balloon #3:

Diagram of ResultsDraw where in the tank each balloon went. Label the balloons “1,” “2,” and “3.”

Student Sheet

Unit 1 • 61




ENGLISH LANGUAGE LEARNERSpromoting Use of Native Languages Encouraging ELLs to use their native languages helps students access science content and feel more comfortable in the classroom. It can be especially valuable for activities, such as this one, that require discussion of complicated explanations and reasoning. If possible, assign students to be in the same group as at least one other student that speaks the same native language, and invite students to discuss in their native languages as they work to solve the mystery.

SCIENCE NOTESAbout mystery balloon Results: Don’t reveal this information to students! The ice balloon floats high on the surface, the salty room-temperature balloon sinks to the bottom, the hot freshwater balloon floats on the surface, a bit lower than the ice balloon, and the cold freshwater balloon sinks at first and then starts to rise as it warms up. The ice- and hot-water balloons float horizontally, while the cold-water balloon floats vertically until it warms up. You may want to watch the demonstration tank closely as students are doing their investigations, and call attention to it when you notice the cold-water balloon starting to rise and change from vertical to horizontal.

About the Importance of predictions in Science. Scientists often make predictions before observing a model, a lab investigation, or the natural world. Scientists base their predictions on the evidence they already have. They realize, however, that they will gain more evidence from their observations, which may show that their predictions were incorrect. The goal of making a prediction is not to guess correctly, but rather to clarify one’s thinking. Making a prediction helps a scientist make explicit how she thinks something will work. If observations match the prediction, it may be evidence to support the idea about how something works. If observations do not match the prediction, the scientist knows she may need to change her ideas.

About Reducing variables. In science, the idea of testing only one thing (variable) at a time means that you can isolate the effect of that variable on the outcome of the experiment, allowing you to be more sure of the effect of that variable on the results. If only one variable in an experiment is changed, then it is clear that any resulting effect is caused by that particular variable.



7. Project slide; describe recording results in two places. After the group tries a balloon in the test tank and watches it for about 30 seconds, they will write what actually happened in the Results column and describe why they think that happened. They will also record the position of the balloon by adding it to the illustration of the test tank on their data sheet. Remind students not to change their predictions after they see what happens. But they can record if a balloon changes from its initial position by adding arrows to their drawings.

8. Introduce Balloon Investigation Results chart. Show students the chart you posted (see Figure 1–7) and tell them that you want one person from each group to record their group’s results on the class chart as they complete each balloon investigation. Describe how they will write the type of water they used on a sticky note, and then place the sticky note on the class chart to show if the balloon sank, floated or went somewhere between. Encourage them to place the sticky note on the chart to show the relative position of the balloon after watching it for about 30 seconds in the test tank. If the balloon changed position during the investigation, they can note that on the chart.

9. Groups start investigations. Ask students if they have any questions. Caution them not to rush, and tell them it’s fine if they complete only one balloon test because everyone will share results later. Tell them that they will have about 12–15 minutes and have them begin.

10. Circulate as groups work. Go around the room encouraging the groups to discuss their predictions and record their reasoning on their data sheets. Also remind them to record their results on the class chart. Give students a five-minute, and then later a one-minute warning to start cleaning up materials. Remind students to record their results on the large class chart if they haven’t done so yet.

11. Stop the activity. Stop the activity when there are about 5 minutes left in the session or when every group has completed and recorded at least one balloon test. Have someone from each group move the tank and the tray of materials to an area away from students. Have each group keep their data sheet.


Unit 1 • 63




INSTRUCTIONAL SUGGESTIONSAlternative to Tying balloons. Provide a small rubber band for those students who have trouble tying off the balloons, or place students in groups with at least one student who is able to tie balloons.

Reducing Distractions. Before the debrief, you may want to have students place all their materials on their trays and move everything to the side of the room to reduce distractions during the debrief.

Balloon Investigation Results

hot fresh-water

hot fresh-water

room temp fresh cold

fresh-water

room temp salt

cold salt water

Figure 1–7. Having one member from each group add appropriately positioned sticky notes to a posted class chart after each balloon is tested provides a powerful visual tool for sharing class results.


mySTERy OF THE FLOATING bALLOONSSESSION 1.5

Discussing Group Results and mystery balloons 1. Look again at the large container and balloons. Ask students to look

again at the demonstration container and balloons to see if anything has changed. Have volunteers describe any changes and record the results on the Floating Balloons Mystery Demonstration chart by adding arrows to show if there was movement. [Cold balloon that originally sank and then rose and floated vertically, is now floating horizontally at the surface because the water in the balloon warmed up to room temperature. Hot balloon may be floating a bit lower in the water since the water in the balloon cooled off to the temperature of the tank. Salty balloon is still on the bottom. Ice balloon is warming up and floating a bit lower because the ice is melting and the water in the balloon is becoming denser.]

2. Discuss sources of evidence. Tell students that they will now try to explain what kinds of water are in the mystery balloons. Say, “You have a few sources of evidence you can use to try to figure out what kinds of water are in the mystery balloons. You will use your observations of the mystery balloons—whether they sank, floated, or went somewhere between. You will use what you have learned about density, molecules, and temperature. And you will use your observations of the balloons you tested with your group.”

3. Groups discuss mystery balloons. Tell groups that they will try to figure out what was in one or more of the four mystery balloons in your demonstration. Give groups a minute or two to discuss. (If time permits, you might want to have groups select one balloon, and use the optional sheet to write their responses.)

4. Class discusses mystery balloons. Call on a volunteer to share her idea about what kind of water is in one of the mystery balloons and what evidence supports her idea. Invite other students to respond by asking questions, agreeing and adding more evidence, or disagreeing and explaining why. Continue for as many ideas about mystery balloons as time allows. Tell students that in the next session they’ll find out about what was in each mystery balloon, and students will also find out what density of molecules has to do with why the balloons sank or floated.

5. Collect data sheets. Collect each group’s Balloon Investigation Data Sheet to be used again in the next session.

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Solving a Floating Balloons MysteryChoose one of the Mystery Balloons from the class demonstration. Tell what kind of water you think was in that balloon and the evidence that makes you think so. Use evidence from your observation of what the balloon did in the tank, tests that you or another group did with balloons in the smaller tanks, and what you have learned about temperature, molecules, and density.

Mystery Balloon Color __________________

Location of the mystery balloon in the tank___________________

We think this balloon was filled with _____________________________________________

water. This is the evidence that makes us think that:

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(where it ended up in tank)

(optional) Student Sheet

Unit 1 • 65




SCIENCE NOTESAbout the Unique properties of water. Water is a unique substance in that it becomes less dense when it is solid (ice). This is due to the arrangement of the hydrogen and oxygen atoms from different water molecules that prevents them from being very closely packed together as they combine into ice crystals. When water solidifies, the molecules form a rigid lattice structure where they are further apart than when they are in a liquid state.

pROvIDING mORE EXpERIENCEReinforce: Illustrate key Concept. Have students illustrate the key concept presented near the beginning of this session. Students should include labels and/or a caption to explain their illustrations.

Reinforce: writing about One mystery balloon. If possible, have each student write an explanation telling what kind of water they think is in one of the mystery balloons and what evidence makes them think that. Make one copy of the Solving a Floating Balloon Mystery student sheet (in Copymaster Packet) for each student. Having students complete this in class allows students to discuss evidence with their groups, which can be quite helpful, but you can also assign this as homework.

Extend: Reflection prompts for the Session. • What do you think density has to do with whether or not the

balloons floated in the tank? • Draw a diagram and explain in words where you predict a balloon

filled with the following liquids would float in a tank of room-temperature water: cold salt water, room-temperature salt water, cold water, hot salt water.

• Draw a diagram comparing what you think the molecules would look like in each of the following balloons: cold salt water, room-temperature salt water, cold water, hot salt water. [This prompt is especially good for more-advanced students.]

Figure 1–8. Water molecules behave the opposite of what you’d expect. They are more tightly packed when they are liquid (left) than when they are solid. Ice is less dense than liquid water since its molecules are farther apart (right).


Unit Goalsscience content• The Ocean as a Heat Reservoir• Density and Movement of

Ocean and Air Currents• Water Cycle

practices of science• Making explanations from

evidence• Using models

natUre of science• Scientific explanations are based

on evidence• Technology plays a role in

gathering new evidence

science lanGUaGe• Using science vocabulary• Having evidence-based

discussions

Ocean Literacy Scope and Sequence and Climate Literacy principle Correlations Ocean Literacy S&S 1.B.4. Ocean water gets denser as salinity increases and as temperature decreases.Climate Literacy Principle 5.A. Our understanding of the climate system is improved through observations, theoretical studies, and modeling.

Session 1.6

Balloon Simulations

Students review the results from the balloon investigations in the last session and solve the Mystery of the Floating Balloons. Through discussions and a quick-writing assignment, students make connections between their test-balloon results and

concepts about the density of molecules. Finally, groups design and test more balloon investigations, this time using a computer simulation. Student learning is focused on the following key concept:

• Denser substances sink below substances that are less dense.

Students also learn:

• There are two ways water can become denser: (1) it gets colder or (2) it has matter, such as salt, added. In both cases, there would be more molecules in the same amount of space, and those molecules would be less far apart from one another and more tightly packed.

• Cold water is denser than warm water, and salty water is denser than less salty water.

balloon Simulations Estimated Time

Reviewing Floating Balloons Mystery Results 5 minutesMaking the Connection to Molecules and Density 15 minutes

Designing Balloon Simulation Investigations 10 minutes

Conducting Simulation Investigations 15 minutes

Total 45 minutes

Unit 1 • 67

What You Need

Next Generation Science Standards (NGSS) Correlations Available online: www.mare.lawrencehallofscience.org/oss68



Session 1.6

Balloon SimulationsFor the class:

❏ simulation, Density of Liquids ❏ projection system* ❏ computer with Internet connection* or resource disc ❏ 1 slide for Session 1.6 ❏ Floating Balloons Mystery Demonstration chart (from Session 1.5) ❏ Balloon Investigation Results chart (from Session 1.5) ❏ masking tape ❏ 3 clear plastic cups (9 oz) ❏ marbles ❏ ¾ cup salt

For each group of students ❏ 2 sets of Molecule Cards* (from Session 1.5) ❏ completed group student sheets, Balloon Investigation Data Sheet (from

Session 1.5)

For each student: ❏ Investigation Notebook: pages: 5–8, 26–27; optional page 25 (DWR)

*not provided in kit

GETTING READybefore the day of the session: 1. Set up projection system/review multimedia. Set up and test the projection

system to be sure all students will be able to see items projected during the session. Spend a few minutes reviewing this session’s materials and supplemental resources found at mare.lawrencehallofscience.org/oss68 or by following the links (eBook) or using the resource disc (print version).

2. prepare marble cups. Fill two cups about ¾ full with marbles. Measure out about ¾ cup of salt into a third cup.

3. preview the simulation. Project Density of Liquids before the session until you are comfortable dragging and dropping different balloons into the tank and changing the liquid in the tank. Try viewing the balloons in Molecular View.


SESSION TITLE HERE OkSESSION 1.6

Reviewing Floating balloons mystery Results1. Review data. Seat students in the same groups of four as in

the previous session. Give each group their completed Balloon Investigation Data Sheet. Have them briefly review the sheet and the data on the class charts, Floating Balloons Mystery Demonstration and Balloon Investigation Results.

2. Briefly discuss results. Ask, “In your group’s tests, which water balloons sank in the tank of slightly warm water?” [Whatever other results they report, make sure students agree that balloons filled with salty, room-temperature water sank.] Ask, “What kinds of balloons floated?” [Hot-water balloons.]

3. Briefly discuss each mystery balloon Review the ideas the class discussed for what kind of water could be in each mystery balloon. If there were mystery balloons you did not have a chance to discuss in the previous session, invite students to share their ideas now about what was in those balloons.

4. Review end-of-session, mystery-balloon evidence. Students may have noticed that one of the balloons (cold water) sank at first, but later started to rise (as the water in the balloon warmed up to room temperature). Encourage students to use this additional evidence of what happened over time to decide which of the alternate ideas about what was in the mystery balloons is likely to be correct. Finally, confirm that the two mystery balloons that sank were different. One was cold water, which later rose as it warmed, and the other was salty room-temperature water. The balloon that floated was hot water, and the other floating balloon was ice.

bALLOON SImULATIONS

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Balloon Investigation Data SheetDecide what to put in each balloon. Predict what will happen when you place the filled balloon in a tank of slightly warm water. Record the type of water and your prediction, as well as evidence for your prediction, in the table. Once the first two columns are filled in, test the balloon. Then, record your results, both in the table and in the diagram below.

Group Members _____________________________________________________________

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PREDICTIONDo you think the balloon will sink, fl oat, or go between? Why do you think that?

RESULTWhat happened?


Balloon #1:

Balloon #2:

Balloon #3:

Diagram of ResultsDraw where in the tank each balloon went. Label the balloons “1,” “2,” and “3.”

Student Sheet

Unit 1 • 69




DAILy wRITTEN REFLECTIONwrite what you have learned so far about the density of different liquids. This prompt, on page 25 of the Investigation Notebook, asks students to think back to the previous activity and to use the word density to describe their understanding so far. Writing also prepares the students to do further investigations with the balloon simulations in this session.

INSTRUCTIONAL SUGGESTIONSkeep the Review of the mystery balloons brief. Unless you have a long class period, spend only five minutes on the review of last session’s results. Save as much time as possible for the activities that follow.

Explaining to Students why Frozen water Is Less Dense. If students ask why it is that ice, which is colder, floats in room-temperature water, tell them that when water freezes, the molecules get further apart than when they are in a liquid state. This makes water ice less dense than liquid water, and that is why ice floats. You may also want to tell them that freezing usually increases the density of substances, but that water is an exception. Alternatively, you could postpone giving an explanation and tell them that they will be designing investigations for a computer model later in the session where they can test an ice balloon and view how the the molecules are arranged inside.



making the Connection to molecules and Density1. Review key concepts. Tell students that they’ll use what they have

learned about molecules and density to understand the results of the balloon tests. Distribute Investigation Notebooks and have students turn to pages 5–8, Key Concepts. Read aloud the two key concepts from Sessions 1.1 and 1.5:

• When heat energy is added to water, the water molecules move more and get farther apart from one another. This causes the water to expand.

• For any one type of substance, such as water, it will be denser if the molecules are closer together. It will be less dense if the molecules are farther apart.

2. Project slide; students record key concept. Project the key concept and have a student read it aloud. Have students write the key concept below the third guiding question. Ask, “Which is denser, hot water or cold water?” Call on a volunteer to answer and challenge her to explain why. [Cold water is denser because the molecules are closer together.]

3. Model density with marble cups. Show the model to help explain why the salt-water balloon sank. Hold up the two clear cups of marbles and tell students that the marbles represent water molecules. Pour the salt into one of the cups of marbles. Let students see the salt fill in the spaces between the marbles.

4. Why salt water is denser. Explain that salt water is denser than water without salt (freshwater) because there are more molecules (water molecules and salt molecules) packed into the same space. A cup of salt water has more mass (more “stuff”) than a same-size cup of water without salt.

5. Introduce discussion . Tell students that discussing concepts is a great way to understand them better. Partners will explain to each other why the cold-water balloon and the room-temperature, salt-water balloon sank. They can also discuss why other balloons floated or sank. Ask them to use the words dense and molecules as they discuss their ideas. Encourage them to refer to the key concepts and the Balloon Investigation Results chart.

6. Distribute Molecule Cards. Students will use the Molecule Cards in their discussions to help show what they are saying. Pass out a set of Molecule Cards to each pair of students.

bALLOON SImULATIONSSESSION 1.6

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Key Concepts (continued)

Guiding Question #2: How does the ocean affect climate on Earth?

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Guiding Question #3: What is density?

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Student Sheet—Ocean Sciences Sequence 1.1–1.12


Unit 1 • 71




pROvIDING mORE EXpERIENCEprepare: Revisiting the Simulations. Depending on what your students share and their understanding so far, you might want to re-show the two simulations for Session 1.1 to review what happens to molecules when heat is added. Before manipulating the variables, ask students to turn to their partners and tell them to predict whether the molecules will get closer together or move farther apart when heat is added. Then ask them to talk to their partners about what will happen to the molecules when heat is removed.

SCIENCE NOTESAbout the Cups of marbles model. The model with the two cups of marbles does a good job of illustrating how salt water is denser than freshwater because the matter from salt fits into the spaces between water molecules. There are, of course, inaccuracies with this model, some of which you might discuss with your students. Most importantly, in the model, actual salt crystals fit between the representations of water molecules. In real salt water, water molecules are much smaller, so it is not the relatively large crystals of salt that fit between water molecules, but rather the tiny sodium and chlorine atoms which make up salt that fit around the water molecules. (When salt is dissolved in water, the atoms that are bound together by ionic bonds in a salt crystal separate from one another.)

ENGLISH LANGUAGE LEARNERSvocabulary Scaffold. ELLs will likely benefit from a more in-depth treatment of the word density. Have students help you complete a word map on chart paper, as shown below, then post the word map on the wall.

Drawing:

Related words:density

In other languages:

Sentence using density:



7. Turn and Talk. Tell students that they will have about five minutes for their discussions, and have them begin. Circulate and encourage students to use the words dense and molecules; challenge them to use evidence from their investigations and their key concepts. Remind them to use the Molecule Cards in their explanations.

8. Write about density. Regain the attention of the class. Distribute Investigation Notebooks and have students turn to page 26, A Cup of Water. Tell them that they will have just five minutes to write their answers to the question, “What are two ways you could make this water denser?” Explain that the goal is to get their ideas down on paper quickly, so they should not worry too much about spelling or punctuation. Remind them to use the terms molecules and density in their explanations.

Designing balloon Simulation Investigations 1. Introduce the balloon simulation. Tell students that it would be

great to be able to try out many more substances in the balloons or to change the substance in the tank. This would be a lot of work and mess, but it would help them learn more. Tell students that there is a computer simulation that will do this with no mess. Project the simulation, Density of Liquids. Point out on the screen all the possible substances that can go into the balloon or into the tank.

2. Demonstrate investigation design process. Using the simulation and Investigation Notebook page 27, Balloon Simulations, design an investigation together. Tell students that you will select room-temperature water for the tank and salt water for the balloon. Have students record that information in the first two columns. Ask the class to predict what will happen and why, and have students record that information in the third and fourth columns.

3. Do simulation and fill in results. On the screen, drag the balloon to the tank. [It sinks.] Go over how students would fill in the fifth and sixth columns with the result and their explanations. [Balloon sinks. Salt water is denser than freshwater.]

4. Show molecular level on simulation. Reset the simulation to show the molecular level in the balloons. Drop the salt-water balloon in the room-temperature water tank again. Have students describe what they notice to a partner. [There’s more “stuff” (matter) in the salt water. The molecules are closer together.] Tell students that they could add those details about the molecules to their explanations in the sixth column.


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26 Student Sheet—Ocean Sciences Sequence 1.6

Name ___________________________________________ Date _________________________

A Cup of WaterThis is a cup of freshwater at room temperature. What are two ways you could make this water denser?

Be sure to use the words dense and molecules in your explanation.

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27

Name ___________________________________________ Date _________________________


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Unit 1 • 73




ASSESSmENTCritical Juncture: Two ways to make Room-Temperature water Denser. Read student responses on page 26, A Cup of Water, in the Investigation Notebook to gauge how well they understand the molecular ideas related to density. At this point in the unit they should be clear that density is a measure of how closely the molecules are packed together in a particular substance. It will be important for students to understand this idea before moving on to learning about currents in the following sessions. If students are struggling with this, consider conducting the Providing More Experience activity below.

pROvIDING mORE EXpERIENCEReinforce: Differences in water Density—Three Cups of water. Have students draw three cups at the top of a piece of paper and label them “Cold Water,” “Hot Water,” and “Cold, Salty Water.” Lead a class discussion about which cup has the densest water and why. Have students draw molecules in the cups indicating the density differences in each type of water.

SCIENCE NOTESDoes Sample Size matter? This question may arise if students wonder about the balloons being slightly different sizes and whether or not that would affect where they float in the tank. You might ask your students, “Is the density of the substance inside a balloon affected by how much substance is in the balloon?” For example, if two identical balloons were filled with the same substance from the same pitcher, and one balloon were filled only part way so it was half as large as the other, would they float at the same level? (All the air was removed from both the balloons.) There are many ways you might want to have your students investigate this question, including using different-sized pieces of the same material such as different sized pieces of clay, or sand vs. a pebble or rock, or, of course, two different-sized balloons filled with the same substance. They will discover that size is not a factor in the density of a substance and differently-sized pieces of the same material (or balloons filled with the same substance), will be the same density. It is the substance, not the size, that matters.



5. Design investigations to test with the simulation. Tell groups to design two or three investigations that they would like to try. Tell them that they can only try substances that are shown on the screen. For each investigation they plan, they would need to complete the first through fourth columns on the notebook page. They can discuss their choices and their predictions, but each person needs to complete his own Investigation Notebook page.

Conducting Simulation Investigations 1. Describe procedure for doing investigations. Regain students’

attention and describe the class procedure for investigations as follows:

a. If possible, each group will get a turn to request an investigation. They will announce the substances in the tank and balloon, what they predict will happen, and their reasoning.

b. The rest of the class will record the information about the other group’s requested investigation in the first four columns of their Investigation Notebooks.

c. Each small group will discuss the prediction and decide whether or not they agree with the requesting group and why.

d. After the simulation, each small group will record and talk about the results, and write down why they think that happened.

e. The next group will announce their investigation.

2. Groups decide which investigation to conduct. Give groups a minute or two to discuss and decide which of the investigations they listed they would most like the class to conduct.

3. Perform investigations. Try as many of the groups’ requested investigations as there is time. Make sure all students record information about the requested investigations.

4. Preview next session. Tell students that they will do experiments with water in the next session and start to learn how differences in density make water and air move around Earth.

Unit 1 • 75




INSTRUCTIONAL SUGGESTIONSpresentation Options: Do Additional Simulations. If you think your students need more experience connecting molecules and density, do another simulation investigation as a class, this time with hot and cold water. Choose hot water for the tank and cold water for the balloon and/or vice versa. Have students predict to a partner what they think the molecules would look like in each situation, then run the simulation. [The molecules in cold water are closer together than the molecules in warm water.]

presentation Options: Each Group Uses the Simulation. If you have access to multiple student computers or a computer lab, you might want to provide students with the opportunity to try out their investigations in small groups or on their own. Many teachers have found this to be a very feasible option. SMART boards are also a wonderful way to display the simulation for the entire class.

make an Extra Copy of the Data Sheet. If you think you’ll have more time or have groups do the simulations on their own, you might want to make extra copies of the data table on page 27 (Balloon Simulations) in the Investigation Notebook so students will have more opportunities to record data.

pROvIDING mORE EXpERIENCE Reinforce: Connections between key Concepts. Either as a homework assignment or using extra class time, have each student select two or three key concepts from pages 5–8 in their Investigation Notebooks that they think are closely related. Have students write a short paragraph explaining why these ideas are connected.

Extend: Reflection prompts for the Session.• Describe how you would explain what density is to someone who

had never heard about it before. • Why do you think it might be important to understand density

when studying the ocean and the atmosphere?

session 1.5 mystery of the floating balloons sapaytan...session 1.5 mystery of the floating balloons...

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