WATER CHEMISTRY • WATER PRESSURE

Title: Ten Fathoms Under the Sea

(Water Pressure)

Grade Level(s): 6-8

Introduction: Pressure is defined as the force per unit area exerted upon an object. Changes in pressure lead to the development of winds, which in turn influence our daily weather. Water pressure changes with depth due to the amount of force being exerted. The amount of time that a diver can remain under water depends largely on water pressure. As a diver descends the surrounding water pressure increases causing a slight discomfort in their ears and sinuses. Divers relieve this discomfort through equalizing by holding their noses and blowing gently, or swallowing. Decompression sickness, also called the bends, is an injury that occurs if a diver ascends too quickly or dives too deeply for too long.

Learner Objectives:

• Students will determine how water pressure differs at various depths by observing water flow.
  
  
• Students will determine how scuba diving and lung capacity is affected by changes in water pressure.

Florida Sunshine State Standards: Science: SC.C.2.3.3.1, SC.D.1.3.3; Math: MA.E.1.3.1, MA.E.1.3.3.

Competency-Based Curriculum: Science: Sci.M/J3 III-1-A
Math: M/J1 V-2-A Math.M/J3 VI-7-A

Materials:

tin cans
container of water with small cup
masking tape
shallow basin to collect water
paper towels
lab worksheet

Activity Procedures:

1. Divide the class into groups of four and assign each student one of the following roles. Each group needs to have all of the materials listed.
   1. Materials- to collect and maintain materials needed for lab.
      
   2. Recorder- to record information from the lab on the Worksheet.
      
   3. Technician- to perform manipulation of the lab work.
      
   4. Maintenance- to clean up the lab station and be prepared for any mishaps(spills).
2. The group should form a hypothesis for the results and the recorder should record these on the Lab Worksheet.
3. Place the tin can in a shallow basin with the holes plugged by masking tape.
   
   
4. Fill the can with enough water to cover each hole. Make sure that no water is leaking from the tape.
   
   
5. While holding the can with one hand, the technician removes the tape. Observe and record.
   
   
6. Which hole has the stronger stream? Which hole has the weaker stream? Why?

Student Assessment:

Ask one student from each group to share lab results and discuss the results that each individual group discovered. Develop rubrics for assessing student work.

Activity Extensions:

Encourage interested students to contact a local diving shop or certified diving instructor to find out how the special equipment worn by deep-sea divers controls pressure. (Science, Physical Education)

Home Learning Activity:

Have students write and illustrate a story describing the changes in fluid pressure experienced by a diver as he/she rises from the ocean floor to the surface.

Vocabulary: Pressure, decompression sickness, equalization

References/Related Links:

http://encarta.msn.com/index/conciseindex
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/home.rxml
www.aquanet.com
http://www.mtsinai.org/pulmonary/books/scuba