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1.7: Does warm and salty water sink?

	Does warm salty water float or sink?
	Planning an investigation
	Performing an investigation
	Data analysis and Science Talk
	Evaluating a Design Solution

I can plan an investigation to test differences in density between water types and develop a model showing particle changes in different types of water

PS3-4 Heat Energy Transfer

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Does warm salty water float or sink?

Slide 2

How will this investigative question help us to figure out if the proposed design solution will work?

Site of proposed design solution

Knowing if warm salty water floats or sinks helps us to figure out __________ part of design solution.

Independently write down the data students would like to collect. Give students a couple of minutes to write down any type of data we would want to collect to figure out if there is a measurable difference in these different types of water that could explain why one might float and one might sink. Students may suggest a variety of possible ideas, including ones related to measuring temperature, weight or mass, and maybe even volume.

Say, So some of us suggested weight or mass as one type of measurement, and maybe we will want to take other measurements too. So let’s plan to record that on the board. I have some cold water set aside for use in our lab, and I also have some warmer water too, which is at room temperature, as well as salty water. Let’s start with some of the warmer fresh water and take a couple measurements together to work through some of the details of what data we want to collect and how we can all go about comparing it across groups. If students suggest recording temperature, then say that we can record that too and do so.

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Group Roles

Slide 3

1- Clarifier

2- Reporter

3- Facilitator

4- Questioner

In addition to normal roles, do this:

Facilitator- Keep the group on task, invite each member to share ideas

Reporter- Be sure that all materials are cleaned up and/or put away after use

Questioner- Get shared materials and return them right away!

Clarifier- Main recorder on chart paper for group

Independently write down the data students would like to collect. Give students a couple of minutes to write down any type of data we would want to collect to figure out if there is a measurable difference in these different types of water that could explain why one might float and one might sink. Students may suggest a variety of possible ideas, including ones related to measuring temperature, weight or mass, and maybe even volume.

Say, So some of us suggested weight or mass as one type of measurement, and maybe we will want to take other measurements too. So let’s plan to record that on the board. I have some cold water set aside for use in our lab, and I also have some warmer water too, which is at room temperature, as well as salty water. Let’s start with some of the warmer fresh water and take a couple measurements together to work through some of the details of what data we want to collect and how we can all go about comparing it across groups. If students suggest recording temperature, then say that we can record that too and do so.

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Planning an Investigation- on chart paper

Slide 4

Set up a procedure for your investigation. You may have more than one investigation that you want to try.

Most dense layer sinks, least dense layer floats

Step 1: Label beakers with types of solutions you will test

2: Add 50 ml of cold freshwater to a beaker (stays colorless)

3: Add 50 ml of warm freshwater to a beaker

4: Add food coloring

5:________________…..

Next slide directions- use slides 4-5 to help you plan investigation

Independently write down the data students would like to collect. Give students a couple of minutes to write down any type of data we would want to collect to figure out if there is a measurable difference in these different types of water that could explain why one might float and one might sink. Students may suggest a variety of possible ideas, including ones related to measuring temperature, weight or mass, and maybe even volume.

Say, So some of us suggested weight or mass as one type of measurement, and maybe we will want to take other measurements too. So let’s plan to record that on the board. I have some cold water set aside for use in our lab, and I also have some warmer water too, which is at room temperature, as well as salty water. Let’s start with some of the warmer fresh water and take a couple measurements together to work through some of the details of what data we want to collect and how we can all go about comparing it across groups. If students suggest recording temperature, then say that we can record that too and do so.

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Before Starting Investigation

Slide 5

You can make revisions to your procedure based on what you saw from other groups

Review the next slides (7-12) in your folder about what to add or specific investigative techniques (this can help you too if you’re stuck on your procedure)

Facilitator, Get your procedure checked by a teacher and then you can do your investigation

Reminder: Use the techniques listed on the next slides to help you make your salt solutions and take measurements during the lab

Gather students around a demonstration area. Students should bring their science notebooks with the prepared data table. Invite students to ask questions and record observations.

Review how to measure mass on a digital scale as a class. Follow the procedures and prompts below. The purpose of this demonstration is to remind students how to use an electronic scale with the tare function and discuss the importance of the meniscus.

Place the electronic scale on a flat surface. Press the "ON'' button and wait for the scale to show zeros on the digital screen.
Weigh the graduated cylinder with ~50 mL of fresh room temperature water in it.
Place an empty graduated cylinder on the scale. Press the "Tare" or "Zero" button to automatically deduct the weight of the container. The digital display will show zero again.
Carefully add the cold, ~40 mL fresh room temperature water to the 2nd 100-mL graduated cylinder.
Record the mass of the system now.

Measure the accurate mass of the water. Students do not have to take down these specific measurements because they will collect their own data in their groups. Each group will be assigned a target volume to shoot for, which they will try to keep relatively consistent across their four water conditions. But, make sure the mass of this sample you measured together as a class is now written on the board. You will add a volume measurement next to it in a moment.

Discuss other measurements we want to take.

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Remember to use your Roles While Working

Slide 6

STOP: REMEMBER TO HAVE YOUR

PROCEDURE AND EXPERIMENTAL SET UP

CHECKED BEFORE STARTING

1- Clarifier

2- Reporter

3- Facilitator

4- Questioner

In addition to normal roles, do this:

Facilitator- Keep the group on task, invite each member to share ideas

Reporter- Be sure that all materials are cleaned up and/or put away after use

Questioner- Get shared materials and return them right away!

Clarifier- Main recorder on chart paper for group

Independently write down the data students would like to collect. Give students a couple of minutes to write down any type of data we would want to collect to figure out if there is a measurable difference in these different types of water that could explain why one might float and one might sink. Students may suggest a variety of possible ideas, including ones related to measuring temperature, weight or mass, and maybe even volume.

Say, So some of us suggested weight or mass as one type of measurement, and maybe we will want to take other measurements too. So let’s plan to record that on the board. I have some cold water set aside for use in our lab, and I also have some warmer water too, which is at room temperature, as well as salty water. Let’s start with some of the warmer fresh water and take a couple measurements together to work through some of the details of what data we want to collect and how we can all go about comparing it across groups. If students suggest recording temperature, then say that we can record that too and do so.

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Take Temp. data in addition to what you have in your procedure

Slide 7

STOP: REMEMBER TO HAVE YOUR PROCEDURE AND EXPERIMENTAL SET UP CHECKED BEFORE STARTING

Add this to Poster

Take the temperature of each initial solution and final solution after you mix one or more types of water

Fresh cold water can be colorless!!

Sample Data Tables

Type of Water	Color	Initial temperature

Creating salt solutions:

50ml of type of water

5.4 g of salt

Types of water mixed	Color	Final temperature	Observations

Gather students around a demonstration area. Students should bring their science notebooks with the prepared data table. Invite students to ask questions and record observations.

Review how to measure mass on a digital scale as a class. Follow the procedures and prompts below. The purpose of this demonstration is to remind students how to use an electronic scale with the tare function and discuss the importance of the meniscus.

Place the electronic scale on a flat surface. Press the "ON'' button and wait for the scale to show zeros on the digital screen.
Weigh the graduated cylinder with ~50 mL of fresh room temperature water in it.
Place an empty graduated cylinder on the scale. Press the "Tare" or "Zero" button to automatically deduct the weight of the container. The digital display will show zero again.
Carefully add the cold, ~40 mL fresh room temperature water to the 2nd 100-mL graduated cylinder.
Record the mass of the system now.

Measure the accurate mass of the water. Students do not have to take down these specific measurements because they will collect their own data in their groups. Each group will be assigned a target volume to shoot for, which they will try to keep relatively consistent across their four water conditions. But, make sure the mass of this sample you measured together as a class is now written on the board. You will add a volume measurement next to it in a moment.

Discuss other measurements we want to take.

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Creating your Salty Water

Slide 8

STOP: REMEMBER TO HAVE YOUR PROCEDURE AND EXPERIMENTAL SET UP CHECKED BEFORE STARTING

1) Measure 50ml of water into a graduated cylinder and pour into a beaker

2) Turn the Power button on

3) Place a weigh boat onto the balance

4) Press the TARE button to zero the balance (make sure it is measuring in grams)

5) Use the scoopula or spoon to measure 5.4g of salt

6) Fold the weigh boat and pour into the beaker with 50 ml of water

7) Add food coloring to the solution in the beaker. Use different colors for each different type of solution. Cold freshwater can stay colorless.

Gather students around a demonstration area. Students should bring their science notebooks with the prepared data table. Invite students to ask questions and record observations.

Review how to measure mass on a digital scale as a class. Follow the procedures and prompts below. The purpose of this demonstration is to remind students how to use an electronic scale with the tare function and discuss the importance of the meniscus.

Place the electronic scale on a flat surface. Press the "ON'' button and wait for the scale to show zeros on the digital screen.
Weigh the graduated cylinder with ~50 mL of fresh room temperature water in it.
Place an empty graduated cylinder on the scale. Press the "Tare" or "Zero" button to automatically deduct the weight of the container. The digital display will show zero again.
Carefully add the cold, ~40 mL fresh room temperature water to the 2nd 100-mL graduated cylinder.
Record the mass of the system now.

Measure the accurate mass of the water. Students do not have to take down these specific measurements because they will collect their own data in their groups. Each group will be assigned a target volume to shoot for, which they will try to keep relatively consistent across their four water conditions. But, make sure the mass of this sample you measured together as a class is now written on the board. You will add a volume measurement next to it in a moment.

Discuss other measurements we want to take.

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Measuring Volume

Slide 9

Measure the bottom of the meniscus

STOP: REMEMBER TO HAVE YOUR PROCEDURE AND EXPERIMENTAL SET UP CHECKED BEFORE STARTING

Measure 50ml of water to make salt solutions using graduated cylinder, then pour into a beaker

Discuss the importance of the meniscus. Follow the same procedure above to measure the mass of the fresh cold water. When you add the water to the 100-mL graduated cylinder (model using the plastic pipette for accuracy). Say, The water in the cylinder will form a curve called the meniscus. Hold the graduated cylinder at eye level and take your measurement from the center of the meniscus. Ask a student to measure the volume of the water currently in the graduated cylinder. If students report a volume to the nearest mL, ask if the meniscus is exactly on a line or somewhere in between. If somewhere in between, ask students to estimate the volume to the nearest 0.1 mL.

Record the volume reported (in mL) on the board next to its mass (in g).

Plot the single data point that you measured (volume, mass) on a sticky circle at the corresponding coordinate location on the piece of poster graph paper. Say, OK, we have one point of data for one of the four types of water samples we want to collect data on.

Emphasize that the qualitative reasoning we’ve done so far about volume and mass makes sense, that when one goes up the other would go up, and when one goes down the other would go down for the same substance. Suggest that now that we have exact values for the mass and volume of this sample, we might be able to make a more exact prediction about their relationship by engaging in the first strategy for developing mathematical and computational models introduced in lesson 2, which is posted on the related anchor chart from that lesson:

"Predict what would happen to a given variable if you scaled up or down (e.g. doubled, tripled, halved) a different variable."

Suggest that we use that strategy again now. Display slide I.

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GETTING YOUR WATER

Slide 10

STOP: REMEMBER TO HAVE YOUR PROCEDURE AND EXPERIMENTAL SET UP CHECKED BEFORE STARTING

QUESTIONER:

ASK TEACHER FOR COLD WATER WHEN YOU’RE READY

IF YOU’RE HEATING WATER, USE THE MICROWAVE

PRESS COOK TIME → SET FOR 10 SECONDS

In addition to normal roles, do this:

Facilitator- Keep the group on task, invite each member to share ideas

Reporter- Be sure that all materials are cleaned up and/or put away after use

Questioner- Get shared materials and return them right away!

Clarifier- Main recorder on chart paper for group

Gather students around a demonstration area. Students should bring their science notebooks with the prepared data table. Invite students to ask questions and record observations.

Review how to measure mass on a digital scale as a class. Follow the procedures and prompts below. The purpose of this demonstration is to remind students how to use an electronic scale with the tare function and discuss the importance of the meniscus.

Place the electronic scale on a flat surface. Press the "ON'' button and wait for the scale to show zeros on the digital screen.
Weigh the graduated cylinder with ~50 mL of fresh room temperature water in it.
Place an empty graduated cylinder on the scale. Press the "Tare" or "Zero" button to automatically deduct the weight of the container. The digital display will show zero again.
Carefully add the cold, ~40 mL fresh room temperature water to the 2nd 100-mL graduated cylinder.
Record the mass of the system now.

Measure the accurate mass of the water. Students do not have to take down these specific measurements because they will collect their own data in their groups. Each group will be assigned a target volume to shoot for, which they will try to keep relatively consistent across their four water conditions. But, make sure the mass of this sample you measured together as a class is now written on the board. You will add a volume measurement next to it in a moment.

Discuss other measurements we want to take.

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When Mixing Water

Slide 11

STOP: REMEMBER TO HAVE YOUR PROCEDURE AND EXPERIMENTAL SET UP CHECKED BEFORE STARTING

1) Add solution first to the graduated cylinder

2) Add solution to your pipet

3) Carefully lower your pipet tip to the surface of the water

4) Add dropwise

5) Observe and record

Gather students around a demonstration area. Students should bring their science notebooks with the prepared data table. Invite students to ask questions and record observations.

Review how to measure mass on a digital scale as a class. Follow the procedures and prompts below. The purpose of this demonstration is to remind students how to use an electronic scale with the tare function and discuss the importance of the meniscus.

Place the electronic scale on a flat surface. Press the "ON'' button and wait for the scale to show zeros on the digital screen.
Weigh the graduated cylinder with ~50 mL of fresh room temperature water in it.
Place an empty graduated cylinder on the scale. Press the "Tare" or "Zero" button to automatically deduct the weight of the container. The digital display will show zero again.
Carefully add the cold, ~40 mL fresh room temperature water to the 2nd 100-mL graduated cylinder.
Record the mass of the system now.

Measure the accurate mass of the water. Students do not have to take down these specific measurements because they will collect their own data in their groups. Each group will be assigned a target volume to shoot for, which they will try to keep relatively consistent across their four water conditions. But, make sure the mass of this sample you measured together as a class is now written on the board. You will add a volume measurement next to it in a moment.

Discuss other measurements we want to take.

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Slide 12

Record Observations and Data on Posters

As a Group

Record observations and data on your chart paper
Add zoom in bubbles to your experimental set up to show particle drawings

# of particles and type of particles
Arrangement of particles (mass of particles within a certain volume or space ~ density)
speed of particles

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Slide 13

Analysis

Discuss and add to your posters:

1)Which is more dense, hot or cold water? Use particle drawings to explain why.

2) How does adding salt affect water’s density?

3) What happened when we added the warm salty water and ice cold fresh water? Use your particle drawings to explain why that happened?

4) What patterns, if any, do you notice about your final temperature values? Use heat transfer to explain any patterns that you notice?

Be prepared to use this information to share during our science talk!

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Slide 14

Science Talk

During Science talk: Record in Notebook

New ideas, thoughts, questions that you might want to add to your group’s poster

Use your science communication toolkit in your folder to help you contribute to the science talk

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Slide 15

Science Talk Reflection

What did we do well as a class?
What could we improve for next science talk?

Use your science communication toolkit in your folder for ideas about what we did well and could improve

Ask reflection questions at the end- Looking at the communication toolkit what did we do well? What could we improve? (3 responses to each)

Ask for gots and needs from science talk at end

Conduct a whole-group Consensus Discussion about the water-density layering demonstration.

Listen for these ideas:

Though density is a property for a substance at room temperature, temperature increases tend to increase the distance between those particles, and thus decrease the density of the particles that make up that substance.
When denser fluids are moved beneath less dense fluid, they tend to remain separated and flow independently of each other.

Summarize the class discussion. Say, Let’s try to explain these results beyond just saying that it is due to density differences. Let’s get ready to show what we think is different at a particle level to explain why one liquid is denser than another.

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Slide 16

Add to your poster- Science Talk

Use what you recorded and learned from the science talk to add to your group posters

Which is more dense, hot or cold water? Use particle drawings to explain why.
How does adding salt affect water’s density?
What happened when we added the warm salty water and ice cold fresh water? Use your particle drawings to explain why that happened?
What patterns, if any, do you notice about your final temperature values? Use heat transfer to explain any patterns that you notice?

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Slide 17

Thermal Equilibrium

3:30-4:19

3 min total after 1.5 min. Remind partners to switch and move to next question

3 min. To call on students to share answers with class

Conduct a whole-group Consensus Discussion about the water-density layering demonstration.

Listen for these ideas:

Though density is a property for a substance at room temperature, temperature increases tend to increase the distance between those particles, and thus decrease the density of the particles that make up that substance.
When denser fluids are moved beneath less dense fluid, they tend to remain separated and flow independently of each other.

Summarize the class discussion. Say, Let’s try to explain these results beyond just saying that it is due to density differences. Let’s get ready to show what we think is different at a particle level to explain why one liquid is denser than another.

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Slide 18

Thermal Equilibrium

Partners 1 and 3: Explain in your own words how the diagram is showing a transfer of heat or thermal energy. (hint look at the colors to explain)

Partners 2 and 4: Explain how temperature is related to the heat transfer showed. (hint: what do you notice about starting and final temperatures?)

3 min total after 1.5 min. Remind partners to switch and move to next question

3 min. To call on students to share answers with class

Conduct a whole-group Consensus Discussion about the water-density layering demonstration.

Listen for these ideas:

Though density is a property for a substance at room temperature, temperature increases tend to increase the distance between those particles, and thus decrease the density of the particles that make up that substance.
When denser fluids are moved beneath less dense fluid, they tend to remain separated and flow independently of each other.

Summarize the class discussion. Say, Let’s try to explain these results beyond just saying that it is due to density differences. Let’s get ready to show what we think is different at a particle level to explain why one liquid is denser than another.

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Slide 19

Add to Poster Drawings

Use your temperature data to justify that heat transfer occurred as different types of solutions were mixed together.

Use your particle drawings to explain why all solutions that mix will eventually reach thermal equilibrium despite differences in density.

10 min- add this plus finish up with posters to turn in

Conduct a whole-group Consensus Discussion about the water-density layering demonstration.

Listen for these ideas:

Though density is a property for a substance at room temperature, temperature increases tend to increase the distance between those particles, and thus decrease the density of the particles that make up that substance.
When denser fluids are moved beneath less dense fluid, they tend to remain separated and flow independently of each other.

Summarize the class discussion. Say, Let’s try to explain these results beyond just saying that it is due to density differences. Let’s get ready to show what we think is different at a particle level to explain why one liquid is denser than another.

https://www.youtube.com/watch?v=vcgYQ-u7qfc Thermal equilibrium demo

https://www.youtube.com/watch?v=870y6GUKbwc Transfer of energy between molecules (3:30-4:19)

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Slide 20

Evaluating the Design Solution

Turn and Talk

Partner 1 and 3: Do you think the salty warm water flows along the bottom of the basin and then rises up under icefjord to start melting the iceberg?

Partner 2 and 4: What parts of raising the sill will help prevent ice melt? What might not work?

Site of proposed design solution