1. Introduce or review the concept of adaptations.
Write the word adaptation on the board. Ask students to define this word as it relates to animals. Ask:

• Why do animals have special adaptations to their habitats?
• What examples of animal adaptation can you think of near where you live?
• What types of adaptations in marine animals have you previously learned about?

Encourage students to think about adaptations in marine animals related to obtaining food, providing camouflage or safety from predators, or dealing with changes in temperature, salinity, pressure, lack of sunlight, and need for oxygen.

2. Have students identify animal adaptations in a National Geographic photo gallery.
Show students the photo gallery and have them take turns reading aloud the captions as the class looks at each photo. Ask students to identify information about adaptations in each caption. For those captions that do not include adaptation information, challenge students to find visual evidence of adaptation. For example, needlefish travel in schools to protect themselves from predators; their color and size help them blend into their surroundings. Portuguese man-of-wars have air bladders that allow them to float on or near the surface of the ocean. These communal organisms use their air bladders like sails, allowing wind to move them through the water. The green sea turtle’s shell protects it from predators.

3. Have students make predictions about ocean habitats.
Ask students to predict how different ocean habitats might affect the animal adaptations seen there. Ask:

• How different is life at the surface of the ocean from life at the bottom?
• What types of adaptations might marine animals need to have near the surface versus near the bottom?

1. Activate prior knowledge by introducing or reintroducing James Cameron’s historic Challenger Deep dive.
Explain that Cameron’s submersible was under 8 tons of pressure per square inch while he was in the Challenger Deep at depths of up to 10,898 meters (35,756 feet). Ask: Could Cameron (or any person) survive under that much pressure at those depths without being protected inside of something? Could other living creatures survive at those depths and that pressure? How? What other living creatures do you think Cameron was likely to encounter at those depths?

2. Divide students into pairs and have them review the characteristics of the ocean zones and match ocean animals with the ocean zones in which the animals are found.
Briefly review the characteristics of each ocean zone, using the provided NOAA Layers of the Ocean website if necessary to refresh students’ memories. Give each pair of students a photo of an ocean animal from one of the provided websites or point them to an animal on one of the websites. Have students look at the photos of the animals, read the captions, and list as many characteristics and adaptations of the animals as they can. Then have them compare the lists of characteristics and adaptations to the different ocean zones to predict in which zones the creatures live.

3. Have students investigate the hadalpelagic zone.
Distribute the Deep-Sea Creature Project Planner worksheet to each pair of students. Have students read the information about the Mariana Trench from the provided DEEPSEA CHALLENGE, Windows to the Universe, and NOAA Layers of the Ocean websites. Have them list unique characteristics of the hadalpelagic zone in the first column of the worksheet.

4. Have students brainstorm adaptations related to the characteristics of the hadalpelagic zone.
For each characteristic of the hadalpelagic zone that students listed on the Deep-Sea Creature Project Planner worksheet, have them brainstorm possible adaptations that would allow an animal to survive and thrive in a place with that characteristic. Ask them to also consider adaptations related to senses or physical characteristics that would not be needed there. For example, if they listed that the hadalpelagic zone is dark, they might include adaptations such as acute hearing or sonar to aid in navigation and/or the loss of eyesight because it would be of little use in that environment. Encourage students to list as many possible adaptations as they can.

5. Have students predict what Cameron saw on his dive by drawing never-before-discovered creatures that could survive in the Challenger Deep in the Mariana Trench.
Distribute the Deep-Sea Creatures Rubric, paper, pencils, and colored pencils, pens, or markers to each pair of students. Review the Deep-Sea Creatures Rubric with students and make sure they understand how they will be assessed. Ask students to select adaptations for their animals from their brainstormed lists. Adaptations should cover all the unique characteristics of the hadalpelagic zone, although some adaptations might address more than one characteristic. Have students draw, color, and clearly label their creatures.

6. Have students share their creatures with each other.
Arrange the class into groups of two to three pairs each. Have each pair present its creature to the other pair(s) in the group and describe how the creature is adapted for survival in the hadalpelagic zone.  After group members have presented to each other, display all the creatures in the classroom and give students a chance to walk around and look at each other’s work. Use the Deep-Sea Creature Rubric to assess students’ creatures. Discuss how the creatures are similar to and different from one another. Ask: How does the diversity of the creatures you and your classmates designed compare to the diversity of real animals in the hadalpelagic zone?

7. Show the "Absolute Edge of Life" video and discuss what James Cameron actually saw during his historic dive into the Mariana Trench.
Ask: How did your predictions compare to what Cameron saw? How was what Cameron saw different from what he expected to see? What lesson did he take away from that? Do you believe there are animals in the deep oceans that haven’t been discovered yet? Why or why not?

1. Activate prior knowledge by reintroducing James Cameron’s DEEPSEA CHALLENGE expedition to the Mariana Trench.

Review the DEEPSEA CHALLENGE website to refresh students’ memories about the expedition. Have students brainstorm what they remember from previous activities about conditions in the trench and about the kinds of adaptations animals have developed to survive in those areas. Ask students to rephrase some of those adaptations as problem-solution pairs. For example: no light (problem)-bioluminescence (solution).

2. Project the provided handout James Cameron’s Quote about the DEEPSEA CHALLENGE Expedition and read it with students.

Discuss the quote from James Cameron. Ask: What was his motivation for designing the DEEPSEA CHALLENGER submersible? Why was designing a new submersible necessary? Explain that Cameron and his team had to engineer a submersible that was specifically adapted to explore the deep ocean. Brainstorm challenges that Cameron and his team had to address in order to explore in the hadalpelagic zone. Elicit responses that include that they had to be able to withstand 8 tons per square inch of pressure, be able to operate in near-freezing temperatures, have time to explore the bottom, and provide some sort of lighting for visibility. Have students read and discuss the DEEPSEA CHALLENGE: The Sub website to identify some of the solutions Cameron and his team of engineers came up with for these challenges. As students discuss and share ideas, create a list on the board of problems and solutions related to the expedition.

3. Ask students to describe what an engineer is and what an engineer does.

Accept multiple answers from students and write them on the board. Encourage students to think about what they have read about James Cameron and the team of engineers that designed the DEEPSEA CHALLENGER. Then review what you wrote on the board and guide students to come up with a working definition of an engineer. Explain that engineers follow a general procedure to solve an engineering problem or design a solution. Distribute the Engineering Process handout and review the steps in the process with students. When reviewing step 1, define the terms “constraints” and “considerations,” and give examples of each. Constraints are absolute requirements or limitations in a design or decision-making process. If a choice or solution doesn’t meet the constraints, then it must be eliminated. For example, if you are shopping for new bookshelves for your living room, there will be a size constraint. The bookshelves must be small enough to fit in the available space in your living room. Any bookshelves that are too big must be eliminated as a choice, even if they are otherwise perfect. Considerations are desired, but not necessary, elements in a design, solution, or decision. Considerations can be used to rank choices and solutions. For example, if your living room has a lot of dark wood, the tone of the wood for your bookshelves would be a consideration; you might prefer to have dark wood so that it will match the other wood in the room. However, you wouldn’t necessarily eliminate a shelf just because it has lighter wood.

4. Introduce the idea of biomimicry through examples and a guessing game.

Explain that animal adaptations like the ones students explored in the Adapting Under Pressure activity can sometimes be a source of inspiration for engineers who are trying to solve a particular design challenge. Open the provided Humpback Breaching webpage and read aloud to students the last bullet point, which explains how the whale is an inspiration for cutting-edge technology. Discuss what biomimicry is and why looking at examples from nature might be helpful to engineers. Divide students into small groups. Display three examples of biomimicry from the provided WebEcoist: Brilliant Bio-Design webpage, and have students work with their groups to identify the inspiration from nature behind these designs.

5. Focus students’ attention on one of the engineering challenges faced by James Cameron and his team.

Provide students with the following focus questions:

• What heat-related problem did James Cameron face in early dives? What caused the problem?
• What effect did the heat have on Cameron?
• What solutions did he and his team come up with to address the problem?

Show the "105 Degrees" video and have students use the focus questions to take notes as they view the video. Then have students read the description of the dangers from extreme temperatures faced during the DEEPSEA CHALLENGE dive from the provided DEEPSEA CHALLENGE Expedition Risks and Dangers website. Discuss the focus questions and the reading as a class.

6. Have students make observations about the effects of extreme heat and cold on a marshmallow.

Place a large marshmallow in boiling or near-boiling water for about 30 seconds to one minute. Spoon the marshmallow out of the water and show it to students. Ask students to make observations about what happened to the marshmallow. Students should observe that the marshmallow melted or got smaller. Place another marshmallow in ice water for 30 seconds to one minute and then pass it around to students. Have students make observations about what happened to the marshmallow. They might observe that it shrank slightly, and they should definitely observe that it became very cold to the touch. Explain that students will be using marshmallows as stand-ins for explorers in an engineering challenge of their own.

7. Have students redefine the problem statement.

Challenge students to work in small groups to come up with designs inspired by nature that will protect their explorers (represented by the marshmallow) from extreme heat (boiling or near-boiling water) and extreme cold (ice water). Read aloud to students the problem description section of the Problem Scenario: Engineering Inspirations handout. Explain that students will use the Engineering Process handout they were given earlier to guide them through the process as they plan, design, and test solutions to the problem presented in the scenario. Working in small groups, have students define the problem in their own words per step 1 of the Engineering Process handout. Invite groups to share their problem definitions with the class, and then go over the problem definition provided on the Problem Scenario: Engineering Inspirations handout. Briefly review the concepts of constraints and considerations. Have each group list constraints and considerations for the problem scenario. Have groups share their ideas with the class, and then provide the final list of constraints for the problem as listed on the Problem Scenario: Engineering Inspirations handout.

8. Have students conduct research that will help them solve the problem.

Explain that students should utilize biomimicry and look for inspiration from nature to help them solve the problem. Have each group brainstorm questions they have, information they need, and keywords and topics to use in their research to solve the problem, and have them list these per step 2 of the Engineering Process handout. Have students use the provided National Geographic Animal Photo gallery to look for inspiration. Also allow time for them to conduct research about any other information they identified as important to their solutions.  Have students summarize the results of their research and describe their inspirations from nature per step 2 of the Engineering Process handout.

9. Have students propose solutions.

Have students review the problem, including the constraints and considerations they identified. Students should then propose solutions based on inspiration from nature and describe their solutions per step 3 of the Engineering Process handout. Encourage students to be specific and thorough in their proposals.

10. Have students develop designs.

Have students draw detailed designs for their proposed solutions as described by step 4 of the Engineering Process handout. Have them label their designs, include possible materials, and make any other notes necessary for clarity. Ask students to describe how they think their designs will work to solve the problem.

11. Have students build prototypes.

Provide students with materials such as small soda bottles, medicine bottles, small lengths of PVC pipe, a variety of insulating materials (foam pipe insulation, bubble wrap, packing peanuts, etc.), waterproof duct tape, conductive materials (such as aluminum foil), rags, sponges, and other available materials. Have students build prototypes of their designs using these available materials. Remind students of the size constraints for the prototypes. Have students list the materials they use, including amounts, per step 5 of the Engineering Process handout. Have them include step-by-step instructions for how to build the prototypes. Point out that these instructions must be specific and thorough enough that someone else could use them to replicate the prototypes.

12. Have students test the prototypes.

Describe the basic testing procedure to students. Tell them that each group will first immerse their prototype in hot water and then open the prototype and check the status of the marshmallow. They will then use the same prototype to repeat the process in cold water. Tell them that a test using a successful prototype will show no effect on the marshmallow. However, if their marshmallow is altered after the first test they can use a new marshmallow for the second test. Have students specify how they want to conduct the tests per step 6 of the Engineering Process handout. Ask: How will you open the prototype after it is removed from the water? How quickly will you need to open the prototype after it is removed from the water? Have students list the data they need to collect in order to evaluate their solutions and describe how they will use the data to improve their designs. Have students create tables to record the data for each test. Have students conduct the first test in hot water and record their data. Because prototypes will need to be opened in order to check the effects of the test on the marshmallow, students will need to repair the prototypes or use the information they recorded to build identical prototypes for use in the next test. Have them test the prototypes in cold water and record their data. Have students use the data they gathered to evaluate the success of their designs. Have them determine what, if any, changes need to be made to their designs to solve the problem. Give students time to re-make their prototype and make any adjustments needed. Then have them test again. Provide students at least three opportunities to adjust and re-test their prototypes. Make sure they record detailed data for each test, including any adjustments made to their designs. Have students write summaries of their test results and the adjustments they made based on those results.

13. Have students evaluate their final designs and the engineering process.

Have each group present a summary of their design and testing. Discuss the engineering process the students followed and analyze why some designs worked and others did not. Ask: What kinds of materials were used in the successful designs? What functions did those materials serve? Tell students that they will write a reflection of the process they used to solve the problem presented to them. Distribute the Reflection Rubric to each student and review the criteria you will use to assess their written reflections. Tell students to refer to the Engineering Process handout and any other notes they took to write their reflections. Explain that the reflection should include a summary of the problem they had to solve, an explanation of how their design was inspired by nature, and an evaluation of how well their design worked, including what they would change to make it work better. They should then compare what they did in this activity to what an engineer does.

1. Activate students’ prior knowledge by having them list some engineering challenges that James Cameron and his team had to solve in order to travel to the Mariana Trench.
Remind students that Earth’s ocean is largely unexplored in part because of the engineering challenges presented by deep-sea exploration. If necessary, have students visit the provided DEEPSEA CHALLENGE website to review some of the challenges. Distribute the Engineering Process handout and review the steps in the process with students. Tell students that they will be using their journals to respond to prompts in the steps on the Engineering Process handout and to take notes as indicated throughout this activity. When reviewing step 1 of the handout, remind students what constraints and considerations are, and give examples of each. Constraints are absolute requirements or limitations in a design or decision-making process. If a choice or solution doesn’t meet the constraints, then it must be eliminated. For example, if you are shopping for new bookshelves for your living room, there will be a size constraint. The bookshelves must be small enough to fit in the available space in your living room. Any bookshelves that are too big must be eliminated as a choice, even if they are otherwise perfect. Considerations are desired, but not necessary, elements in a design, solution, or decision. Considerations can be used to rank choices and solutions. For example, if your living room has a lot of dark wood, the tone of the wood for your bookshelves would be a consideration; you might prefer to have dark wood so that it will match the other wood in the room. However, you wouldn’t necessarily eliminate a shelf just because it has lighter wood.

2. Watch the "Cracking the Code" video of James Cameron describing one of the major engineering challenges his team faced on the DEEPSEA CHALLENGE expedition.

Provide students with the following focus questions prior to watching the video: What was the big challenge James Cameron describes? Why was this challenge unexpected? What was the problem with commercially available foam? Have students take notes as they watch the video, and use the questions to launch a discussion at the end of the video.

3. Have students describe objects using the terms “positively buoyant,” “negatively buoyant,” and “neutrally buoyant.” 

Have students use the palms of their hands to push several objects to the bottom of a tub of water, and ask students to describe what they feel and see as the objects either remain on the bottom or push on their hands back toward the surface. Include objects that will float as well as objects that will sink. If students do not use the term “buoyant” to describe what they see, introduce the term to them. Explain that objects can be positively, negatively, or neutrally buoyant. Ask students to describe the objects in the tub using these terms. Discuss how pressure is related to buoyancy. Refer to the background information section for support with this discussion.

4. Have students redefine the problem description from the Problem Scenario: You Can Take the Pressure handout in their own words.
Read aloud the problem description section of the Problem Scenario: You Can Take the Pressure handout to students. Explain to students that they will use the Engineering Process handout they were given earlier to plan, design, and test solutions to the problem presented in the scenario. Working in small groups, have students define the problem in their own words per step 1 of the handout. Invite groups to share their problem definitions with the class, and then go over the problem definition provided on the Problem Scenario: You Can Take the Pressure handout. Briefly review the concepts of constraints and considerations. Have each group list constraints and considerations for the problem. Have groups share their ideas with the class, and then provide the final list of constraints for the problem as listed on the Problem Scenario: You Can Take the Pressure handout.

5. Have students conduct research that will help them solve the problem.

Have each group brainstorm questions they have, information they need, and keywords and topics to solve the problem, and have them list these per step 2 of the Engineering Process handout. Have students begin their research by using the MapMaker interactive to find the Mariana Trench on a world map. Ask them to label the trench’s depth and the pressure that would be exerted on the DEEPSEA CHALLENGER at that depth on the map. Have students review information about how much pressure is exerted per foot of water depth and then calculate how much pressure their models will need to withstand at a depth of 3 meters (10 feet). Allow them additional time to conduct research for any information they identified as important to their solutions. Provide students with a variety of materials for use in building their prototypes, such as plastic or Styrofoam cups, small lengths of PVC pipe, a variety of insulating materials (foam pipe insulation, bubble wrap, packing peanuts, etc.), waterproof duct tape, pennies or washers, and other available materials. Ask students to test how the various materials behave in water. Have students summarize the results of their research and list characteristics of the materials they explored per step 2 of the handout. Ask students to predict how they think the materials will react to changes in pressure. Provide each group with a cooler or large bucket filled with water to a depth of about 0.3 meters (1 foot).

6. Have students propose solutions.

Have students review the problem, including the constraints and considerations they identified. Ask students to propose solutions and describe them in their journals (step 3 of the Engineering Process handout). Encourage students to be specific and thorough in their proposals.

7. Have students develop designs.

Have students draw detailed designs for their proposed solutions as described in step 4 of the Engineering Process handout. Have them label their designs, include possible materials, and make any other notes necessary for clarity. Ask students to describe how their designs will work to solve the problem.

8. Have students build prototypes.

Have students build prototypes of their designs, using the available materials they explored in step 5 of the activity. Remind students of the size constraints for their prototypes. Have students list the materials they use, including amounts, per step 5 of the Engineering Process handout. Have them include step-by-step instructions for how to build their prototypes. Point out that these instructions must be specific and thorough enough that someone else could use them to replicate the prototypes.

9. Have students prepare a testing procedure.

Describe the basic testing procedure to students. Tell students that they will conduct three sets of tests: the first set will use containers of water filled to a depth of about 0.3 meters (1 foot); the second and third sets will use water up to 3 meters (10 feet) deep. The deeper water tests will be done in a teacher-created water column (see Preparation section and How to Build a Water Column handout for information). Tell students that they will be able to test, evaluate, adjust their prototypes, and retest at each level.  Following step 6 of the Engineering Process handout, have students list the data they need to collect in order to evaluate their solutions and describe how they will use that data to improve their designs. Have students specify how they want to conduct the tests. Ask: How will you collect data? What role will each team member play in the testing process? Have students create tables to record the data for each test. Review the testing procedures with each group before moving on to the next step. Check to be sure that students plan to gather basic data such as the depth of the test, the orientation of the prototype as it ascends, and the length of time it takes to rise to the surface.

10. Have students conduct the first test in 0.3 meters (1 foot) of water.

Have students test their prototypes in 0.3 meters (1 foot) of water and record their data. To conduct a test, students will need to push their prototypes to the bottom of the container and then let go of them to determine whether they are positively buoyant and thus able to rise to the surface on their own. The slower a prototype rises, the closer it is to being neutrally buoyant. A negatively buoyant prototype will remain on the bottom of the container. Have students use the data they collect to evaluate the success of their designs. Have them determine what, if any, changes need to be made to their designs to have them better solve the problem. Give students time to re-make their prototypes and make any adjustments needed. Then have them test again. Provide students as many opportunities as time permits to test and retest their prototypes in 0.3 meters (1 foot) of water.

11. Have students conduct tests at depths of 1.5 meters (5 feet) and 3 meters (10 feet).

Next, give students two opportunities to test at 1.5 meters (5 feet) and two opportunities to test at 3 meters (10 feet), using a water column. For each test, students should use a pole to submerge their prototype to the designated depth and should then remove the pole to see what happens to the prototype. A negatively buoyant prototype will sink; a neutrally buoyant prototype will hover at the depth where it is released, and a positively buoyant prototype will rise to the surface. The slower a positively buoyant prototype rises, the closer it is to being neutrally buoyant. Encourage students to consider the differences in pressure between the two sets of tests and make adjustments accordingly. A prototype that is positively buoyant at 1.5 meters (5 feet) might or might not remain positively buoyant at 3 meters (10 feet). Make sure students record detailed data for each test, including any adjustments made to their designs. Have students write summaries of their test results and the adjustments they made based on those results.

12. Have students evaluate the final designs and the engineering process.

Have each group present a summary of their design and the results of their tests. Discuss the engineering process the students followed and analyze why some designs worked and others did not. Ask: What kinds of materials were used in the successful designs? What functions did those materials serve? What effect did pressure have on the prototypes as they dove deeper? How did those effects match the predictions you made in step 5 of the activity? What adjustments did you make to counteract those effects? Read the provided DEEPSEA CHALLENGE: Systems and Technology website and discuss how James Cameron and his team solved the problem of the foam. Tell students that they will write reflections of the process they used to solve the problem presented to them. Distribute the Reflection Rubric to each student and review the criteria you will use to assess their written reflections. Tell students to refer to the Engineering Process handout, their journals, and any other notes they took to write their reflections. Explain that the reflections should include summaries of the problem they had to solve, explanations of how pressure affected their designs in deeper water, and evaluations of how well their designs worked, including what they would change to make them work better.

1. Activate students’ prior knowledge with a game of “Would You Rather.”
Designate one wall as “A” and one wall as “B.” Have students come to the center of the room. Read each of the questions on the "Would You Rather" Questions handout, and have students indicate their response by moving to the wall that matches their choices. After each question, ask a few students to explain their responses. Use the explanations for each Would You Rather question to focus students’ thinking on the concepts being addressed.
 

2. Discuss the relationship among force, pressure, and area using the examples from the Would You Rather game.
Remind students of the cleat example from the previous step. Ask: What would happen to the pressure you would feel on your foot if the person standing on your foot got heavier? Would the pressure increase or decrease? Why? Ask students to think about a person pushing a needle into leather. Ask: If the person were to increase the force with which he or she is pushing the needle, what would happen to the pressure of the needle on the leather? Draw a simple graph on the board and label the y-axis “pressure” and the x-axis “force.” Do not include any numbers. Ask a volunteer to draw a line on the graph illustrating what happens to pressure as force increases. (The slope of the line increases.) Ask another volunteer to draw a line illustrating what happens to pressure as force decreases. (This line will be the same as the previous line.) Remind students again of the example of an elephant on a marble from the previous step. Ask: What would happen to the pressure of the elephant on your foot if the elephant were to balance on a hockey puck instead of on a marble? (It would decrease.) What if the elephant balanced on a dictionary? (It would decrease even more.) Draw a new graph on the board and label the y-axis “pressure” and the x-axis “area.” Have a volunteer draw a line on the graph to show what happens to pressure as area increases. (The slope of the line decreases.) Have another volunteer draw a line to show what happens to pressure as area decreases. (This line will be the same as the previous line.) Ask students to look at the graphs and describe the relationship between force and pressure (directly proportional) and area and pressure (inversely proportional).

3. Introduce the formula for pressure and apply it to a Would You Rather game example.
Write the formula for pressure on the board (pressure = force/area). Refer again to the cleat example from the Would You Rather game, this time plugging in actual numbers (a person weighing 50 kilograms (110 pounds) and wearing shoes with cleats that have a total area of 13 square centimeters (2 square inches)) into the formula. Demonstrate how to calculate the pressure. Ask: What would happen to the pressure if the person wearing the cleats weighed only 41 kilograms (90 pounds)? Write out the formula using the new weight, and calculate the pressure. Ask: What would happen to the pressure if the 41 kilogram (90 pound) person were wearing shoes with larger cleats that have a total area of 19 square centimeters (3 square inches)? Again write out the formula using the new numbers, and calculate the pressure.

4. Divide students into pairs and have them create pressure-related Would You Rather questions for each other.
Have students come up with scenarios and then manipulate one of the variables in the pressure formula to create Would You Rather questions. Ask each pair to write down at least three questions. Play Would You Rather again, this time inviting a few pairs to ask one of their questions. Collect students’ questions for an informal assessment of their understanding of pressure.

5. Have students model pressure using wooden blocks.
Distribute a large rectangular wooden block, 10 pennies or washers, and a small container of sand or flour to each pair of students. Challenge students to use these items to model different pressures by changing just one variable (for example, laying a block in the sand on its smallest side will create a slightly deeper impression than laying it on one of its larger sides). Have students describe each trial and what changed during that trial in their science journals. After students have had a few minutes to experiment with the blocks, ask for volunteers to demonstrate their models. Ask students to identify the variable in the pressure formula that changed in each of the models. Ask them to use their models to describe the relationships among pressure, force, and area.

6. Introduce the DEEPSEA CHALLENGE expedition to students.
Explain that you will watch a brief video describing a historic manned dive to the deepest known part of the ocean. Provide students with the following focus questions:

• Who manned the submersible?
• Where did the submersible dive?
• What effect did pressure have on the submersible under water?
• What did James Cameron do once he reached the bottom of the Mariana Trench?
• Why was the dive important?

Ask students to take notes on these questions as they watch the video. Show the National Geographic News video "James Cameron Breaks Solo Dive Record." At the end of the video, discuss the focus questions. Ask students if they were surprised to hear how much the submersible shrank due to the pressure of the water. Ask: Why was the pressure on the submersible so great in the Mariana Trench? Which variable from the pressure formula changed as the submersible went deeper? How did it change? Why?

7. Use a model to introduce the idea that pressure can vary greatly depending on where you are on the planet.
Remind students that molecules in the air and water molecules have mass and therefore exert force. The force applied by the molecules over a specific area equals the pressure of the molecules on the area. Explain that air pressure and water pressure vary based on your elevation above sea level or your depth in the water; note that other variables such as volume and temperature can also influence pressure calculations. Place a marshmallow in the bottom of a test tube, and fill the test tube with cotton balls. Explain that the marshmallow represents a person, and the cotton balls represent molecules in the air. Explain that this model shows a person at sea level. Remove the marshmallow and cotton balls. Replace half of the cotton balls, then place the marshmallow on top of them and fill the test tube with additional cotton balls. Explain that this model shows a person on a mountaintop. Ask: At which location will air pressure likely be greater? (Air pressure will likely be greater at sea level because the air is denser there than at the top of a mountain. There are more molecules in the air, each of which has mass, pressing down on a person at sea level than on the top of a mountain.) Explain that, in general, air pressure decreases as you go up in elevation, although other factors such as temperature and humidity can also affect air pressure. Empty the test tube and place the marshmallow at the bottom again. This time, fill the test tube with marbles and explain that they represent water molecules. Ask students what they think the model represents (a person under water). Rearrange the items in the test tube so the marshmallow is close to the middle of the test tube. Ask students to explain this new model in relation to the previous one. (The person is now in water that is less deep). Ask: In which of these two models would the person be under more pressure? (The model showing the person in deeper water.) Why? (Pressure on a person increases in deeper water because there is more water and thus more mass above the person.)

8. Have students locate Mount Everest and the Mariana Trench using a wall map or the MapMaker Interactive.
Have students place a marker to indicate each location. Give students the elevation of each location and have them add that information to the map as well. Ask: In which location would the pressure exerted on a person be greater? Why? Ask students to predict how much greater the pressure would be at one location versus the other. Distribute the Comparing Pressure handout to each pair of students and ask students to compare their predictions to the actual pressure difference between Mount Everest and the Mariana Trench. Review the handout with students. Explain that the pressures listed on the handout are averages since other factors can also influence air pressure.

9. Explain that students will use the data from the Comparing Pressure handout to create a visual model showing the general differences in pressure at different locations on Earth.
Distribute poster board, pens, beans, rulers, glue, and the Modeling Pressure handout to each pair. Review the handout with students and answer any questions they might have about the activity. Allow time for students to create their models. When students have finished, have them reference their models to write a brief explanation of why pressure is different at different places on Earth. Use the answer key provided in the Assessment section to assess students’ explanations.