What is a Greenhouse?
In class, in newspapers, or on TV, you have probably heard of the 'greenhouse
effect.' In order to understand what this is, you need to first understand how
a real greenhouse works.
Greenhouses are used extensively by botanists, commercial plant growers, and
dedicated gardeners. Particularly in cool climates, greenhouses are useful for
growing and propagating plants because they both allow sunlight to enter and
prevent heat from escaping. The transparent covering of the greenhouse allows
visible light to enter unhindered, where it warms the interior as it is absorbed
by the material within. The transparent covering also prevents the heat from
leaving by reflecting the energy back into the interior and preventing outside
winds from carrying it away.
In this activity you will be building and investigating a simple model greenhouse.
Materials (per team)
- Two two-liter plastic soda bottle "experimental chambers" (instructions
- Two 14- to 16-oz. plastic containers at least 4 1/2 inches in diameter
at the top (sour cream, cottage cheese, or deli containers work well)
- Knife or scissors
- Two thermometers
- One 150-watt floodlight and stand
According to your teacher's directions, form teams of four and gather the materials
A. Experimental chamber construction
For each chamber, you will need a two-liter plastic soda bottle (with cap)
and a 14- to 16-oz. plastic container for the base.
- Remove the bottle label by soaking it in warm water.
- Cut off the end of the bottle approximately 2 inches from the bottom and
discard the bottom piece.
- Place the capped bottle in the plastic base and the experimental chamber
is ready for use.
B. Experimental Procedure
- Use scissors to cut several elongated vents (1 x 4 inches) in the sides
of one of the bottles. Leave the second bottle intact.
- Tape a thermometer (using cellophane tape or light-colored masking tape,
not black electrical tape) to the inside of each bottle (facing out). Make
sure the bulbs of the thermometers are above the top of the chamber base.
(See graphic below.)
- Place caps on both bottles.
- Place both bottles approximately six inches away from the lamp with the
thermometers facing away from the light. DON'T TURN ON THE LAMP.
- Predict which bottle will get hotter when you turn on the light.
- Turn on the light and begin collecting data every minute for 20 minutes.
Observations and Questions
Record and graph the data in your lab book or on a separate piece of paper.
Then answer the questions below.
- Compare and contrast the graphed data from the vented bottle and the intact
bottle. What happened? How do you explain your observations?
- Discuss the results with your class and develop some possible explanations.
- Compare and contrast your plastic greenhouse to the greenhouse effect on
When you're finished with the activity, click on Back to Teacher Guide at
the top of the page.