What are Some Substances That Will Cause Algae To Grow? 

Liz Jones                      Yale School Elementary
8141 S. State St.              7025 S. Princeton Ave.
Chicago, Ill. 60619            Chicago, Ill. 60621
(312) 874-5552                 (312) 535-3091

Objective:

Students will learn how to set up a controlled experiment.  Students will be 
able to determine the effects of oil, detergent, copper crystals sulfate and 
lawn fertilizer have on the growth of algae.

Materials Needed:

4 large jars
glass plates (lids)
pond water
markers for glass jars
4 pencils #2
laundry detergent powder
dry lawn fertilizer
copper sulfate crystals
graduated cylinder

Procedure:

1.  Collect 4 quart jars.  Clean each jar with soap thoroughly.  Make sure the 
    jars are rinsed thoroughly, so that there are no leftover traces of 
    chemicals.  Fill each jar about three-fourth full with distilled water. 

2.  To each jar add 10 milliliters of pond water.  Before measuring the pond 
    water, stir the water thoroughly. 

3.  To the first jar, add 15 grams of detergent.  Label this jar #1, detergent.

4.  To the second jar, add 15 grams of lawn fertilizer.  Label this jar #2, lawn 
    fertilizer.

5.  To a third jar, add 3 or 4 small crystals of copper sulfate.  Label this jar 
    #3, crystals copper sulfate.

6.  To a fourth jar, add 15 milliliters of oil.  Label this jar #4, oil.

7.  Do not add anything to the fifth jar.  Label this jar #5, control jar.

8.  Use the glass-marking pencil to mark the water level in each jar and then 
    place a glass plate over each jar.  Prop up one side of the glass plate by 
    laying a pencil over the edge of the jar so that air can get into the jar
    but so that dust and dirt will not settle into the jars from the air. 

9.  Set all the jars in a well-lighted place, but not in direct sunlight.  
    Observe the jars each day for about 2 weeks.  If so much water evaporates 
    from the jars that you think the results will be affected, add distilled 
    water to bring the water back up to its original level. 

Recommended Strategy:
                            
Discuss orally what is meant by a controlled experiment and a variable factor.  
Using two identical plants, have students follow procedures in setting up a 
controlled experiment.  Students will learn how to apply the scientific method 
by setting up an experiment showing the effects various substances have on the 
growth of algae.  Divide students into four groups picking a number 1 thru 4.  
Each group will be given four cleaned jars containing a measured amount of 
distilled water, detergent, oil, lawn fertilizer and copper sulfate.  Students 
will be given a worksheet to answer one of the question stated:  What they 
already know about algae and what they want to learn?  Students will answer the 
follow up questions after the experiment is completed.  What did they learn?  
Students will be given unlabeled pictures of green algae along with a wet mount
of algae.  They will be asked to compare the algae on the wet mount with the 
pictures and to identify the type. 

Analysis:

1. Define scientific method?  What are the steps?
 
2. Why is it important that the jars be cleaned before beginning the project?

3. Which jar do you think will have the greatest and least amount of growth?

4. What might be some reasons why algae would grow in some jars but not in 
   others?   

5. How do you think copper sulfate would affect the growth of algae?

6. What is a controlled experiment?

7. What are the two groups in a controlled experiment?  Explain how they differ.