Presentations by

Eloise Farmer,
Torrington High School
New Hartford, Connecticut

I. Eloise presented Student Investigations in the GSS Population Growth Book:

-- Earlobes: A Study of Human Gene Frequencies in Chapter 3, page 30

-- Adding Armadillos in chapter 2, page 17.

II. Dynamic Equilibrium

[also found on the following web page:
http://www.cssaonline.net/equilibrium.htm]

Introduction

Materials
Clear plastic containers (2), paper cups, water, meter stick.

Methods
Pour water into the plastic containers until the water level is the same in each container. Measure and record the depth of the water. Obtain two paper cups and submerge each in a separate container of water. When given a signal by one of the lab team members, simultaneously pour each cup of water into the other container. Repeat this process four more times, then measure and record the depth of the water. Then repeat the cycle of five transfers two more times, and measure the depth of the water after each cycle. Record your observations.

Pour all of the water into one of the containers. Measure and record the depth of water in that container. Proceed as before. At the beginning, one cup will be empty and the other full. Simulate the pouring with the empty cup at each transfer. As water is put into the empty container, gather as much water as possible in the cup for each transfer. Measure and record the depth of the water after each five transfers, and continue until twenty transfers have been made. If time allows, do the whole procedure again with different starting depths. Dispose of the water and return the materials to the front desk.

Laboratory Report

Prepare a data table to record the changes in the depth of the water in both containers under each set of conditions. The table should have five columns: Time, TriaI Container I, Trial Container 2, Tria1 2 Empty Container, Tria1 2 Full Container. You may add more columns if you collect more data.

Answer the following questions:

1. What happened to the water levels in trials 1 and 2?

2. How would you describe the shape of the graphs from each set of data?

3. In trial two--one of the cups initially has no water in it--what happens to the amount of water transferred from the empty side to the full side as the trial continues?

4. Are the final water levels in each trial the same? Why?

What would happen to the water levels in each system if you continued to transfer equal amounts of water indefinitely? Why?

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