Lesson Plan 1- Lab Activity: How Do Fertilizers Affect Algae Growth (Eutrophication)
using Hydroponics
Grade Level: _7-8 or High School______
Note: This lab can be modified for middle school without the use of colorimeter to
determine absorbance. But can also be used for High School if colorimeter is used for
absorbance.
National Science Content Standards:

Science as inquiry

Populations and Ecosystems
o Populations of organisms can be categorized by the function they serve in an
ecosystem. Plants and some microorganisms are producers—they make their
own food. All animals, including humans, are consumers, which obtain food
by eating other organisms. Decomposers, primarily bacteria and fungi, are
consumers that use waste materials and dead organisms for food. Food webs
identify the relationships among producers, consumers, and decomposers in
an ecosystem.
o The number of organisms an ecosystem can support depends on the
resources available and abiotic factors, such as quantity of light and water,
range of temperatures, and soil composition. Given adequate biotic and
abiotic resources and no disease or predators, populations (including
humans) increase at rapid rates. Lack of resources and other factors, such as
predation and climate, limit the growth of populations in specific niches in
the ecosystem.
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Lab Activity: How Do Fertilizers Affect Algae Growth (Eutrophication)
using Hydroponics
Introduction:
Hydroponics is the process of growing plants in liquid, with added nutrients but
without soil. By using hydroponics the plant has the ability to grow much faster and be
more portable. Hydroponics can also show the growth of algae, which is eutrophication.
Fertilizer can cause an increase of algae growth. In this lab activity, you will determine if
varying amounts of fertilizer can affect the growth of algae.
Hypothesis: If more/less (circle) fertilizer is added, then the algae growth will
increase/decrease (circle).
Engaging activity:

Video: Eutrophication- What is it?
http://www.youtube.com/watch?v=UGqZsSuG7ao

Video: Demonstrate what is hydroponics first with video (see attached video in
Lesson 1 Folder).
Materials:
 Five water bottles of the same type, 1 quart Gatorade bottle (make sure bottle is
clear)
 Duct tape
 Scissors
 10 mL, 25 mL, 100 mL Graduated cylinder
 Pippettes
 Algae Solution
 Tap water
 Miracle grow liquid fertilizer
 Colorimeter Vernier Software
 Logger Pro
 Cubettes for absorbance readings
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Procedures:
Set-up of Four Water Bottles





Control- Tap water only
Bottle #1- Algae with No Fertilizer
Bottle #2- Algae with 25 mL of Miracle Grow
Bottle #3 – Algae with 50 mL of Miracle Grow
Bottle #4- Algae with 100 mL of Miracle Grow
Control
1. Assign the students into groups of 4
2. Label the Control and Bottles 1-4. Have each student work on one bottle each.
3. In Control Bottle - Add 500 mL of tap water
Bottle #1
4.
5.
6.
7.
In the bottle #1 add 500ml of tap water. Make sure to NOT add any fertilizer.
Add 5mL of Algae solution to water bottle using graduated cylinder and pipette
Rip a piece of duct tape and put it on the mouth of the bottle.
Use a scissors or a pencil to poke a hole in the tape so the algae can breath.
Bottle #2
8. In bottle #2 add 500ml of tap water.
9. Use a graduated cylinder and measure 25ml of Miracle grow liquid fertilizer
10. Add the 25ml of Miracle growth to the bottle #2
11. Add 5mL of Algae solution to water bottle using graduated cylinder and pipette
12. Repeat steps 6-7.
Bottle #3
13. For bottle #3 add 500ml of tap water.
14. Measure 50ml of Miracle grow liquid fertilizer.
15. Add the 50ml of liquid fertilizer to the bottle #3
16. Add 5mL of Algae solution to water bottle using graduated cylinder and pipette
17. Repeat steps 6-7.
Bottle #418. For bottle #4 add 500ml of water.
19. Measure 100ml of Miracle grow liquid fertilizer with the graduated cylinder.
20. Add the 100ml of Miracle grow liquid fertilizer to bottle #4
21. Add 5mL of Algae solution to water bottle using graduated cylinder and pipette
22. Repeat steps 6-7.
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Continue Procedures:
23. Place the 5 bottles in the same area. The algae need sunlight to grow.
24. Observe each bottle for 10 days and take data every 2 days.
a. Qualitative data- observations and descriptions of algae growth. Take
pictures of each bottle every other day.
b. Quantitative data-Use Vernier Software Colorimeter to take absorbance
data of chlorophyll at 480 nm. Be sure to calibrate first using distilled water.
Use a different cubette for each water sample. Record absorbance of
chlorophyll and place data in data table below. (For High School Lab)
Figure 1: Colorimeter & Logger Pro Vernier Software
Data:
Table 1: Absorbance data in 10 days (nm)
Data
Day 0
Table
Control
#1
Botttle #1
No
fertilizer
Bottle #2
25 mL
Bottle #3
50 mL
Bottle #4
100 mL
Day 2
Day 4
Day 6
Day 8
Day 10
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Qualitative Observations: with Pictures
Day 0
Day 6
Day 2
Day 8
Day 4
Day 10
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Line Graph of Data--Place below:
Conclusion/Analysis:
1: Which bottle had the most algae growth? What was the absorbance change over time?
2: Which bottle had the least algae growth? What was the absorbance change over time?
3: Did the amount of fertilizer affect the growth of algae based on the experiment? Explain.
How did the control, no fertilizer bottle, vs. bottles with fertilizer affect algae growth?
4: Was your hypothesis supported or refuted? Explain using data from the lab.
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