Prep for Teachers
Before teaching this lesson, make certain that all of your Web sites are bookmarked on all of the computers in your classroom, and that all of the necessary links are still valid and running. Make sure that each lab station has all of the necessary components in place for the start of the lesson. Duplicate all worksheets needed for the lesson before class begins including the Ice Cream Lab & Application Questions, Ice Water Temperature Data Sheet, Storyboard Worksheet, and Ice Trek Worksheet. You may also want to duplicate the Creating a Video Record of Your Project information included in the Student Materials. This provides a step-by-step guide for creating and editing a video using Adobe Premiere software.
When using media, provide students with a FOCUS FOR MEDIA INTERACTION, a specific task to complete and/or information to identify during or after viewing of video segments, Web sites, or other multimedia elements.
Break your class up into pairs of students.
Distribute the Ice Cream Lab & Application Questions Worksheet found in the Student Materials. Review the lab procedure with class before they obtain the materials needed. Ask the class if they have ever wondered what it is about throwing salt on ice that makes it melt. Why does it melt? Where does the heat come from to melt the water? Why does it freeze again on the road at night? These questions and many more about freezing and thawing will be investigated in this lab. Make sure the students understand the instructions provided on the worksheet before beginning.
Distribute the thermometers and milk in the freezer baggies to student pairs. Have them measure the temperature of the milk when they receive it. Remind the class to wipe the milk off the thermometer as they work. Have them add the vanilla or chocolate flavoring. Stir the flavoring in well and record the temperature again. Squeeze about half of the air out of the baggies and seal them to make a water tight container for the milk.
Distribute a baggie of ice cubes to the student pairs. Have the students measure the temperature of the ice in the bag by placing the thermometer in among the ice cubes and waiting 30 to 45 seconds before reading it. Have the students add 2 to 3 spoons of salt in the baggie with the ice, seal the baggie, and shake for one to two minutes until some of the ice melts. Have the students carefully open the ice/water baggie and measure the temperature of the water inside the baggie.
Carefully place the milk baggie inside the ice/water baggie and seal the outer bag with some air in it. Students should toss the baggies back and forth between their hands gently shaking them to make sure that all of the milk comes into contact with the surface of the bag next to the water in the outer bag. As soon as they notice ice crystals forming in the milk, have them stop and carefully open the two baggies to measure the temperature of the liquids inside each. Reseal the baggies and continue shaking gently until the milk is frozen. Remove the frozen ice milk from the ice/water baggie before opening. Record the final temperature of the ice cream and the ice water.
Allow the students to eat their ice milk product. (NOTE TO TEACHER: Check for any pupil with a lactose intolerance or milk allergy prior to this activity.)
Have the students look over the lab activity analysis questions and make some hypotheses as to how they were able to make ice cream in a baggie. Discuss the questions with the class after the pairs have completed the worksheet. What happened after you added the salt to the ice cubes? (The ice started to melt as the salt ions broke apart and interfered with the crystal lattice of the water molecules bonds. The ice water that is formed is actually below freezing: super-cooled). What is the only factor that could have caused the changes shown in Question 1? (The breaking of bonds requires an addition of energy, which comes from the ice. The ionic compound breaking down during the addition of the salt and ice.) What does this tell you about the freezing point temperature of salt water compared to fresh water? (The freezing point temperature of salt water is less than that of fresh water.) Heat energy is needed to change phase from a solid to a liquid. List the possible sources of the heat needed for this phase change in your baggie. (The ice, the milk, the salt, the air in the baggie, the heat from your hands.) Which source do you think is the best possibility and why? (The milk is the best source of heat energy for the melting process because it is a liquid and stores more energy for the phase change than the air or salt do. Your hands do not touch enough area to be effective sources of heat.) In looking at the temperature changes shown on your Data Table, explain how the energy flow of the baggie system resulted in your tasty treat for an end product. Where is the energy flowing from and where is it going to? (The energy flows from the milk to the ice. This removes enough energy to bring about a phase change from liquid to solid.) In the radiator of your car, you put a combination of antifreeze and water to keep your car engine cool in the summer and prevent the radiator from freezing in the winter. Explain how you think this works in terms of what you saw in the experiment you just did. (The material added in the antifreeze to the water in radiators interferes with the bonding of water molecules and the formation of the solid crystal lattice for ice. This allows the water to stay in a liquid form to circulate through the engine and absorb the heat from the engine. In the summer, the same material raises the boiling point of the water and keeps the very hot water from going to a vapor phase. This allows the water to circulate and absorb even more heat energy from the engine -- cooling your motor.)
Place the video in the VCR and CUE it to the start of the tape immediately following the commercial credits where you'll see the tree logo with "Viewers Like You" or "Thank You" under it. Provide students with a FOCUS FOR MEDIA INTERACTION by asking them to carefully note the preparations made by the team for their trip to Antarctica. PLAY the tape until you see two men starting down a dark hallway as the speaker states, "So that's basically all there is to it." PAUSE the tape to discuss what plans had to be made before the trip. (Warm clothing, weight limits on the luggage, checking of equipment, planning the video scenes to be shot.) Ask the class to make a list of what they would need to do if they were planning to go to a frozen lake in their area to collect information about the water there. Discuss their list with the class. (Class lists should include transportation, proper clothing, how to make sure the ice is safe to walk on, how to collect water from under the ice, a map to the area, collecting apparatus, specimen bottles.)
Provide students with a FOCUS FOR MEDIA INTERACTION by asking them to discover what role the ice of Antarctica plays in the Earth System. PLAY the tape until you see the feet of a penguin, just after the narrator has stated, "But there is more to Antarctica than just ice." STOP the tape and CHECK for student comprehension. (Antarctica stores 70% of Earth's fresh water supply, controls Earth's climate, reflects heat energy back into space, chills the ocean waters to create currents, and affects temperature everywhere.)
Provide students with a FOCUS FOR MEDIA INTERACTION by asking the students to go to the computers in groups and look up the local lake ice coverage/depths. They will need to go to the Water in the Earth System Web site you have previously bookmarked. Have them scroll down to the Terrestrial Information chart. They will need to click on the Surf Your Watershed link. Once they are at the Surf your Watershed site, they should locate the local watershed by using the interactive map or typing in the zip code of the area under investigation. They will also need to go to www.maps.com in order to locate any public lakes or ponds they might be able to use for their investigation. CHECK each group's progress and have them post their findings at a central location -- on a poster chart or overhead transparency. Local ice depths may be obtained from river keepers, ice fishers, or the local police in an area.
FAST FORWARD the tape until you see the orange Sprite vehicle driving up to the dive hut as the narrator says, "After a rough hour's ride over the frozen ocean, the team arrives at the dive hut that they have placed next to a rock called Little Razorback Island." Students will now watch another segment of video about divers in Antarctica. Provide students with a FOCUS FOR MEDIA INTERACTION by asking the students how cold they think the water is at the dive site. PLAY the tape until you see the diver entering the water and descending through the ice hole to the bottom as the narrator states, "But diving is what they came to do." PAUSE the tape to discuss the temperature conditions of the water with your students. (The water temperature is 28 degrees -- cold enough to freeze blood! The divers survive due to thermal linings in their wetsuits and limiting exposure -- both surface area (lips only) and time.) Provide students with a FOCUS FOR MEDIA INTERACTION by asking students why the ocean is not frozen solid down to the bottom in these shallow areas. PLAY the tape until you see the brine channels frozen with the starfish on the bottom of the ocean as the narrator says, "...making these frozen tubes." STOP the tape. CHECK for student comprehension by discussing their answers. (The more dense super-cooled brine formed as the surface ice freezes, flows through the less salty seawater causing the tubes to form around the brine solution.)
Have the students return to their computers and provide a FOCUS FOR MEDIA INTERACTION by asking students what has to happen for the water to freeze from liquid to solid. They will need to go to the BrainPOP Web site you previously bookmarked and view the movie on the subject of states of matter. After viewing the movie, have the class discuss why the water freezes with the class. (Heat always travels from areas of higher concentration to areas of lower concentration. The brine solution is super cold -- colder than the ocean water -- so the heat from the ocean water goes into the brine and the result is that the ocean water freezes solid!)
Materials - Learning Activity
- 8 foot long, 1 inch diameter PVC pipe, threaded at one end for a cap (available from most large home building and supply stores such as Home Depot or Lowes)
- 1 threaded cap to seal the end of the PVC pipe OR one inch rubber cork to seal the end of the pipe
- 1 video camera with videocassette
- Meter stick
- Ice auger (available from ice fishing supply stores or sometimes borrowed from parents of students who ice fish)
- Per group of 4-6 students:
- Clean plastic collecting containers -- either pails or bottles (These can sometimes be obtained from your local deli or cafeteria if you ask in advance.)
- Sharpie marking pen
- 1 copy of Data Collection Chart
- 12 water sample bottles for return to classroom (You might try to get large size baby food jars with lids from your students who have infant siblings. Have the jars run through a dishwasher to sterilize.)
- Optional: Winkler water collection device
Students will investigate several bodies of water and choose one that the entire class will use for their lab site. Distribute the
Ice Trek Worksheet
and review the information students should determine about the various bodies of water. Divide your class into groups of approximately four to six students. Ask the groups to each research one local body of water, a lake or pond, which might be suitable for collecting the water samples they will need. They may need to contact local landowners, the park service, the watershed authority, and/or the local police to obtain this information. After the groups have gathered the information, discuss the results of their search and decide as a class on the collection site to be used. (NOTE TO TEACHER: Do not take students out on ice less that 10 inches in depth.)
Have the students calculate the volume of one foot of the inside of the PVC pipe using the following formula:
Volume = πr2h, where r = radius of the inside of the pipe, and h is the height (12 inches)
Use the volume of water calculated to ensure that you have large enough collection buckets for the activity. Mark the pole into one-foot lengths on the outside with a Sharpie marker. Now fill one of your collection pails with the same amount of water you calculated one foot of the pole would hold and mark the water level on the inside of the pail. This is how much water you want to put in each pail as you collect your samples from the lake.
Use a five-gallon pail of water, the PVC pipe, and cork or end-cap to practice gathering your water samples. The pipe acts the same as a large straw from the surface into the water. If you place a straw in water and then cover the top end firmly with your thumb, you can lift the water in the straw out of the glass and dump it in another container by releasing your thumb. The students will need a sturdy chair or stool to stand on in order to practice placing the end-cap (stopper) securely on the top of the pipe and then lifting the pole out of the water and transferring it to another container. They will need to start and stop the flow of water out of the tube by loosening and tightening the cap. (WARNING: Please be careful to have students keep the pole vertical at all times that it has water in it. If they turn it on its side, the water will pour out!)
Explain to the students that they are going to collect water at different depths from the pond and take the temperature as well as bring back samples for further study and analysis. Have each group of students script an introduction of 1 minute for their video. They should be sure to include who the members of the group are and what they are going to do in this experiment. They will need to complete a storyboard for their introduction and planned shots at the site. This storyboard must be approved by the instructor prior to taping and the actual collection activity. Tape the introductions for each group.
The big day! The class goes to the collection site. Distribute the Ice Water Temperature Data Sheet before going to the site and review the material students are responsible for. Be sure the students responsible for taping the activity record some of the surrounding landscape as well as commentary on weather conditions, ice conditions, etc. so you can edit the information in later. Allow the students to work in their groups to collect enough water up to a depth of 6 feet for the class to analyze. You may have one group act as the videographers for all or rotate the duty according to your preference. There should be one data recorder with thermometer for each group to record the temperature of each "foot" of water retrieved. Remember that the first water let out of the pipe is from the greatest depth. You can measure the depth by watching the lines on the side of the pipe as they go under the ice.
Allow the students to create a spreadsheet of their temperature data on the computer and graph the thermacline -- change in temperature with depth. Now look at the water gathered from each foot of water sample and allow it to sit so that the sediment drops to the bottom of the pail. Carefully measure the depth of the sediment if possible or try to pour off the cleared water leaving the sediment in the pail and then weigh the sediment on a scale. Sift the sediment to separate any larger pieces and then have the students look at it with a hand lens or microscope to try to identify any organisms present. Have them draw the results for future work. Complete Analysis Questions Worksheet.
Allow each group to edit their videotape to produce a 10-minute presentation of the project and their results. This may be done on a rotation basis while other groups are working on the water or soil. Use the camera, Adobe Premiere, and the taped raw footage to make final presentation for grading.
Materials - Culminating Activity
Per group of 4-6 students:
Optional: 1 CD-R disc and CD-RW burner
- 1 copy of Grading Rubric
- 1 computer with Adobe Premiere editing software
Have students keep a tally count of all organisms found in the water or soil and research their role in the ecosystem. Are they an indicator of good water/soil or pollution?
Have students conduct water quality or soil analysis test on the materials collected and report back the results.
Have the students look at the sea ice coverage currently shown on the Water in the Earth System Web site. Ask them to research what factors affect this figure.
Have students write a press release of their findings and the significance of this information to the local community.
- Encourage students to participate in local watershed education and pollution control programs. Ask them to contact the local river keeper or water authority for more information on water conditions in the local area.
- Ask students to attend a community planning board/zoning meeting. They will need to take notes of any proposed building or zoning changes made at the meeting. Then research how these changes will affect the local aquifer or water supply.