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Grade Level (s): 6 - 8
Introduction: We all have experienced being inside the ocean and suddenly feeling that the water gets colder or warmer than usual. The ocean water has various temperatures in different regions because the rays of the sun, which warm the surface of the ocean, reach the various parts of the ocean with different intensity.
In this activity, learners will investigate the temperature changes in a column of cold ocean water, which will be exposed to a source of light. Learners will use a TI calculator and the CBL (Calculator Based Laboratory) in conjunction with three temperature probes.
Learner Objectives:
- Describe the heating of the ocean water by the sun or light source.
- Record and observe differential heating of the ocean water with depth.
- Determine a temperature-depth profile of the ocean by graphing the data obtained for temperature and depth.
Florida Sunshine State Standards: Science: SC.A.1.3.1, GLE 1, SC.A.2.3.3, GLE1, SC.B.1.3.5, GLE 1(grade 8), SC.B.2.3.1, GLE 1, SC.H.1.3.2, GLE 1, SC.H.1.3.5, GLE(s) 1,2,3; Math: MA.D.1.3.1, MA.D.1.3.2
Competency-Based Curriculum: Science: M/J1-I.1.A, I.2.A, I.3.A, I.8.A, I.1.B, 1.2.B, IV.1.A; M/J2-I.3.A, M/J2-I.8.B, I.1.B, 1.2.B; M/J3-I.3.A, I.8.A, I.1.B, I.2.B, III.2.A
Materials
TI Graphing calculator
3 Vernier Temperature Probes
TI-Graph Link (optional)
Powdered dye
Ocean water
Ice
Lamp (if done in the lab)
Meter stick
Aquarium (10 gallon, if in the lab)
OR 5 gallon plastic bucket (if on boat)
Activity Procedures:
- Cool the water in the aquarium to about 4°C with ice. Do not go below this temperature. When the desired temperature is reached, remove the excess ice, and stir the water well. (While some members of the group are working on preparing the water tank, the others should be setting up the calculator, CBL, and probes, steps 2 to 7)
- Plug the three temperature probes into the adapter cable in Channels 1,2, and 3 of the CBL System. Use the link cable to connect the CBL to the TI Graphing Calculator. Firmly press in the cable ends.
- Place the tip of the three probes, one at the bottom, one in the middle, and the third one near the top of the aquarium.
- Turn on the CBL unit and the calculator. Start the CHEMBIO program and proceed to the MAIN MENU.
- Set up the calculator and CBL for three temperature probes.
- Select SET UP PROBES from the MAIN MENU
- Enter “3” as the number of probes
- Select TEMPERATURE from the SELECT PROBE menu
- Enter “1” as the channel number, and repeat the last two steps for channels 2 and 3
- Select USE STORED from the CALIBRATION menu
- Set up the calculator and CBL for data collection
- Select COLLECT DATA from the MAIN MENU
- Select TIME GRAPH from the DATA COLLECTION menu
- Enter “15” as the time between samples, in seconds
- Enter “90” and the number of samples (the CLB will collect data for a total of 22.5 minutes)
- Press “Enter”. Select USE TIME SETUP to continue. If you want to change the sample time or sample number, select MODIFY SETUP
- Enter “0” as the minimum temperature (Ymin)
- Enter “25” as the maximum temperature (Ymax)
- Enter “5” as the temperature increment (Yscl)
- Using the meter stick, measure the distance where you need to place the three temperature probes in order to place one near the bottom, the second near the center of the water column, and the third one submerged near the top. Using rubber bands, secure the three temperature probes in their assigned spot on the meter stick. Submerge the meter stick with the three temperature probes.
- If this experiment is done in the lab, a lamp should be set to reflect the light on the top of the tank, 30 cm directly above the center of the tank. At this point, you may turn on the lamp. In the field, the sun will take the place of the lamp.
- Begin to monitor temperature by pressing “Enter.” The temperature readings in °C, are displayed on the calculator in the form of a graph. The CBL will display one of the temperatures; the others can be seen by pressing the “Ch View” button.
- When data collection stops, and “DONE” appears on the CBL screen, press “Enter” to display the graphs of temperature vs. time on the calculator screen. To confirm the temperature values, examine the data points along the curves, As you move the cursor right or left, the time (X) and temperature (Y) values of each data point are displayed below the graph. Determine the maximum temperature and the minimum temperature (round to the nearest 0.1 degree Centigrade). If graph link and computer are available, print the graph.
- Record the lowest and highest temperature achieved at the levels on the data table.
- Sprinkle a small amount of powdered dye over the water surface. Observe particularly the trails left by the sinking of the heavier particles.
- Blow air gently over the water with the air flowing almost parallel to the water surface. Don’t make waves. Periodically blow from the other direction. The aim is to mix the upper part of the water column until it is a uniform color.
- Measure the lower limit of the dyed layer.
- When you have finished with the model, carefully empty and clean the tank and equipment.
| Data Table |
Section of Aquarium
or Bucket |
Depth (in cm) |
Initial Temperature |
Final Temperature |
| Top |
1 |
1 |
1 |
| Center |
1 |
1 |
1 |
| Bottom |
1 |
1 |
1 |
Observations:
- When adding the dye (step 12):
- When air is blown (step 13)
- Measurement of the lower limit of the dyed layer (step 14)
- Plot a graph of depth (y-axis) versus temperature (x-axis)
Student Assessment:
The students should prepare a lab report, which should include all major parts of a lab report plus the graph and the answers to the following questions:
- Describe the appearance of your graph. What does it indicate? Explain.
- What happens to the temperature as the depth increases?
- Why do you think that the temperature changes differently at the different depths? What happens to the rays of the sun and the heat with depth?
- Will the amount of salt in the water affect your results?
Activity Extensions:
- Obtain lake water and try a similar experiment.
- Compare your results and those of others obtained when samples from more than one source, with different salinity content, are tested.
- Try using two TI/CBL systems and 6 temperature probes with one aquarium to obtain more accurate measurements of the different temperature in the thermocline.
- Interdisciplinary: Search on the internet and write an essay on how the depth and temperatures of the oceans affect the life and the economy of certain cities in the world. (Language Arts, Technology, Social Studies)
Home Learning Activity:
Allow students to bring in samples of water from the ocean, lake, and surrounding areas to measure and compare in the classroom.
Vocabulary: temperature, thermocline
References/Related Links:
Holmquist, D.D., Randall, J., Volz, D.L., (1995) Chemistry with CBL, Portland, OR; Vernier Software
Sager, R.J., Ramsey, W.L.., Phillips. C.R., Watenpaugh, F.M., (1998) Modern Earth Science, Austin, TX; Holt, Rinehart and Winston
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