Beacon Lesson Plan Library

Oxygen Factory

Jacqueline Roberts
Bay District Schools


Through laboratory investigation, students examine the interdependence of the oxygen and carbon dioxide cycle in an ecosystem.


The student knows of the great diversity and interdependence of living things.

The student knows that the chemical elements that make up the molecules of living things are combined and recombined in different ways.



TEACHER DEMONSTRATION 1 (Needs at least 1 hour)
- Small, clear wide mouth jar/or large beaker
- Water
- Leaf
- Magnifying lens
- Sunny location or goose neck lamp

TEACHER DEMONSTRATION 2 (Multiple day 1-3 observation)
- Elodea plant - pet store
- Water
- Deep container
- Clear funnel
- Test tube
- Sunny location or goose neck lamp

- Goggles (all students)
- Aprons (all students)
- 600 ml beaker 3 per group
- Water
- Eye dropper 1 per group
- Bromothymol Blue (BTB)
- Plastic straws (1 per student)
- Elodea plants
- 3 test tubes ( with capability of being sealed - culture tubes with caps if available, if not use corks or aluminum foil and tape) per group
- Test tube holder (clamp)
- Test tube rack

-- Johnson, George B., [Biology: Visualizing Life]. Holt, Rinehart and Winston, Inc., Orlando, Florida, 1994 and 1998.

-- Kaskel, Albert., Hummer, Paul J. and Daniel, Lucille. [Biology: An Everyday Experience]. Charles E. Merrill Publishing Co., Columbus, Ohio, 1988.

-- Strauss, Eric. and Lisowski., [Biology: The Web of Life]. Scott Foresman-Addison Wesley Publishing Co., Atlanta, Georgia, 1998.

-- [Encyclopedia Britannica]. (hardcopy and/or online)

-- VIDEO SERIES: [Science in Action: Photosynthesis and Cellular Respiration], Holt, Rinehart and Winston Inc., 1991.

-- Microslides: [Photosynthesis, Set 59](Can be purchased through any science catalog)


Teacher Preparation (Sequential steps that are numbered in list form):
1. Review oxygen and carbon dioxide cycles.
2. Review leaf physiology.
3. Take inventory of materials and supplies.
4. Set-up Demo 1.
5. Teacher should know that bubbles formed on the surface of the leaves in Demo I is oxygen.
6. Set-up Demo 2.
7. Teacher should know that water is replaced by oxygen in the inverted test tube of Demo 2.
8. Set-up laboratory investigation.
9. Teacher should know Bromothymol Blue (BTB) changes from blue to yellow in the presence of carbon dioxide.
a. When the student exhales through a straw into the beaker, it will change to yellow due to the presence of carbon dioxide.
b. Plant gives off oxygen so the BTB solution will remain blue.

10. Cooperative Learning Group: (Share with students prior to activity)
a. Leader - responsible for coordinating groups activities.
b. Secretary - reads the lab out loud to group and maintains data sheet.
c. Materials Manager - gathers equipment/supplies

Demo 1: Approximately 1 hour
1. Prepare a container of water
2. Place a leaf in the water
3. Place the container with the leaf in a sunny spot or uses a gooseneck lamp to represent sunlight.
4. Ask students to observe the leaf over a period of one hour.
Demo 2: Multiple Day Observation
1. Place a small container (suggest a small aquarium) in a sunny location or near a gooseneck lamp.
2. Fill a deep container with water.
-- Note: To enhance carbon dioxide content add several drops of NaHCO2 to water or bubble gas into water by blowing through a straw.
3. Place an Elodea plant(s) inside the container.
4. Place the clear funnel (wide bottom facing the bottom of the container, the narrow end pointed upward) over the elodea plant(s).
5. Fill the test tube with water and places it (mouth side down) over the clear funnel.
6. Ask students to observe test tube over a period of two to three days.

Laboratory Experiment: Whole Group Preparation
1. Review diversity of living things and interdependence that exists in the environment via oxygen and carbon dioxide continuously cycling through the ecosystem.
2. Review definition of photosynthesis.
3. Demonstrate the experiment.
4. Caution students on safety procedures i.e.
a. Safety goggles and laboratory aprons should be worn through out the investigation.
b. Bromothymol Blue (BTB) stains clothing and is not easily removed. BTB can also be a skin irritant. If it is spilled it must be cleaned-up (flushed with water) immediately.
5. Review clean-up procedures. (Clean-up is everyone's responsibility.)
6. Place 2 to 3 students in cooperative learning groups. (Leader, Secretary, Materials Manager)


NOTE: Please read and follow the directions in the teacher preparation box prior to beginning this lab activitiy.
Part A
Student (secretary) reads lab to group.
Student (materials manager ) gathers all necessary supplies for the lab.
Student (materials manager and leader) sets-up lab according to directions as read by secretary.
Student (secretary) prepares data sheet to record results. (See attachment - chart 1 and chart 2)
All students prepare a hypothesis.

Each student fills a beaker 2/3 full with water.
Each student, in turn, uses an eyedropper to add enough Bromothymol Blue (BTB) to turn water blue (medium blue).
Each student uses a plastic straw to blow (exhale) into the beaker.
Secretary records results. (Chart 1)

Student places masking tape on three test tubes.
Student numbers the test tubes one through three
TEST TUBE 1 - Student places elodea plant in test tube one and fills the test tube with BTB from one of the beakers (part B). Student seals test tube. Student places test tube on test tube rack.
TEST TUBE 2 - Student places BTB solution from beaker (part B) into test tube two. Student seals test tube and places it in the test tube rack.
TEST TUBE 3 - Student places water in test tube three. Student uses eyedropper to add enough BTB to turn Test tube medium blue. Student seals test tube and places it on the test tube rack.
Student places test tube rack in a sunny place or near a gooseneck lamp.
Student records color of test tubes at the beginning of experiment on data chart 2.
Student observes test tubes after one hour and records observations.
Student writes a conclusion.


-- Laboratory Rubric
-- Alternative Assessment (Teacher Choice)
1. Written Assessment - Students write an essay describing how oxygen and carbon dioxide cycle and recycle through an ecosystem.
2. Oral Assessment - Teacher quizzes each student to determine the student's understanding of the oxygen and carbon dioxide cycles.
3. Student to Student Assessment - Student discusses with a partner the oxygen and carbon dioxide cycle of an ecosystem. Each partner, in turn, determines the level of understanding of the partner and gives help where needed. (pair and share)

Web Links

A pre-selected web search results page for photosynthesis
Importance of Photosynthesis

A pre-selected MSN web search results page for photosynthesis
Search results for "photosynthesis"

Web supplement for Oxygen Factory
Photosynthesis Biobook

Photosynthesis Web
Photosynthesis: It brings good things to life

Attached Files

A lab sheet and a rubric.     File Extension: pdf

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