1.4.1 Hot, Cold and Currents
Objective
Students will explore how changes in the salinity and temperature of
water affects its density and motion.
Materials for each group of 3/4 students
- food coloring
- ice cube tray (see Procedure, Step #1-colored ice cube must be made
in advance)
- large glass bowl or small aquarium tank (clear plastic bottles if large
enough)
- hot tap water (43°C or 110°F)
- small bottle of ink
- salt
- test tube or cup
- Celsius or Fahrenheit thermometer
- safety goggles
- Activity 1.4.1 Student Worksheet, "Hot, Cold and Currents"
Engage
In winter months, primary production in the Antarctic Ocean
is nearly zero, which creates difficulty for the grazers who depend on primary
production. But in the 5-6 months of austral spring and summer, these waters
become a nutrient-rich pasture for plankton. The frigid polar waters teem
with life. Part of the reason lies in the density and movement of the water
column which is affected by temperature, salinity, changes in pressure (depth)
and sediment suspension. We can illustrate how these factors work in some
simple lab experiments.
Explore
Procedure
- Organize students into lab teams. Hand out Activity 1.4.1
Student Worksheets and review materials and procedures. Review lab safety
rules. Complete hands-on laboratory investigations.
- When lab is completed, have students share observations
and conclusions. Reinforce relationships between sea ice and ecosystem
in Antarctica.
