Gold Seal Lesson:
How Do Populations Grow?

Copernicus Education Gateway

Subject:

Science

Grade:

9-12

ICLE Standards:

Science: Develop skills in experimental design and procedure; develop an understanding of population growth and limiting factors. Mathematics: Develop numerical recording and graphing skills; apply mathematical predicting skills.

Performance Task:

As we approach the 21st century, the environment continues to be a major issue with which our society and our government must deal. The availability of resources for a growing population is a major part of the environmental debate. In this task, you will examine population growth by creating a living model in the classroom. You will use a lowly water weed, Duckweed (Lemna minor), as your example organism. Carefully follow the steps given below to carry out your inquiry.

1. Fill a petri dish 3/4 full with aquarium water and add 10 drops of nutrient solution ("fertilizer"). Carefully add 25 fronds (leaves) of Duckweed to the dish, being sure to remove any dead, yellowed or tattered fronds. Cover the dish, label with your name and place the dish under a plant grow-light.

2. Every day, count the number of Duckweed fronds in your dish. Record the numbers in a data table.

3. At the end of two weeks, make a line graph of your data. Use the x-axis for "Days" and the y-axis for "Number of Fronds."

4. Use your graph to determine the rate of growth of the Duckweed in "Fronds per Day."

5. Use your graph to make the following predictions:

1. the number of days at which the initial population will have doubled, tripled and quadrupled;
2. the population after three weeks, four weeks and eight weeks;
3. the number of days before the entire surface of the dish will be covered by Duckweed.

In your science journal, write a brief summary of your inquiry, stating what will happen to the Duckweed when it runs out of room and out of nutrients. State how your findings relate to humans and animals. Using your data and understandings obtained in this inquiry, predict the consequences if Duckweed were introduced into a pristine alpine lake such as Lake Tahoe.

Knowledge / Skills:

Know and apply the principles of scientific inquiry.  (s114)

Make observations of the local environment using senses and instruments. Inferences and interpretations are arrived at based on observations. Classify observable properties and organize observations in a meaningful and logical way.  (s5)

Understand ecology as the study of the interactions and relationships of organisms with their living and nonliving environments (i.e., the ecosystem, communities, and populations).  (s13)

Exhibit good data management skills by collecting, organizing, and graphing data.  (s19)

Understand the human impact on the environment through pollution (air, water, and soil), and ways to improve it through education, research, laws, and conservation.  (s10)

Use writing as a tool for learning in formats such as learning logs, laboratory reports, note-taking, and journals.  (ela40)

Rubric:

4 Points  =  The student independently completes all parts of the task. He/she records data in an organized manner, makes a clear graph and makes logical predictions based on observed data. The student demonstrates an understanding of population growth and can apply the concepts to a real world situation.

3 Points  =  The student needs some coaching to complete the task. He/she records all the required data, but data organization is poor. The student has difficulty making a graph from his/her observed data. He/she shows a lack of understanding of population growth and has difficulty making a logical prediction based on the results of the inquiry.

2 Points  =  The student relies heavily on others in his/her attempt to complete the task. The student does not make accurate observations and does not record data in an organized manner. His/her graph is very poorly constructed and contains several inaccuracies. The student's prediction to the real world lacks logical meaning. The student appears to have gained little understanding of the concept of population growth.

1 Point  =  The student does not complete the task and shows no observable understanding of the concepts involved. The student's work is disorganized, inaccurate and incomplete. No graph is produced, and no predictions are made

Keywords:

CHEMISTRY
LAB EXPERIMENTS
DATA COLLECTION
DATA ANALYSIS
DATA DISPLAY
EXPOSITION
INFERENCE

LIFE SCIENCE
PLANTS
POPULATION
VITAL FUNCTIONS                
EARTH SCIENCE
SCIENTIFIC INQUIRY

Grades:

Kg [] - 1 [] - 2 [] - 3 [] - 4 [] - 5 [] - 6 [] - 7 [] - 8 [] - 9 [X] - 10 [X] - 11 [X] - 12 [X]

ICLE Application:

D

© 2000 International Center for Leadership in Education
1587 Route 146 - Rexford - NY - 12148
518.399.2776 Fax: 518.399.7607
97