The Greenhouse Effect
By Erica Hargreave
We have all heard about the greenhouse effect, but how do we explain it to kids without scaring them? First and foremost, introduce the greenhouse effect to kids as a natural process, because it is and without it we would not have life as we know it on this planet – it would be too cold! Secondly, we need to let kids know that humans are releasing additional greenhouse gases into our atmosphere that can be destructive to our planet and our way of life. As a result of this, we need to act now to prevent further damage to our planet. Focus on what we can do to be proactive – how can we prevent further damage to the planet. As it is the children’s generation that will shoulder the brunt of our actions, it is important that they understand what the greenhouse effect is and what they can do to keep our planet healthy. Read on for the science of the greenhouse effect and activities that you can do with your students to explain what the greenhouse effect is and how we can prevent further damage to our planet.
Preparation for The Greenhouse Effect
- Gather supplies.
- Make a sample pop bottle greenhouses – horizontal, vertical, pop bottle planter.
Activity 1: Pop Bottle Greenhouses Demonstration
- One Clear Pop Bottle with a Lid
- Two Thermometers
- Desk Lamp
- To illustrate how the Greenhouse Effect works, set up two thermometers – one inside a clear pop bottle and one outside.
- Seal the bottle with its lid.
- Place both thermometers under a lamp and turn it on.
- Leave the thermometers for at least 20 minutes before checking their temperatures.
What temperature did each thermometer reach? Why are the temperatures of the two thermometers different?
Activity 2: Pop Bottle Greenhouses Planters
- A Class Set of Clear Plastic Pop Bottle with Lids
- A Class Set of Plastic Cups
- Potting Soil
- Easy Grow Seeds (i.e. beans)
- Exacto Knife or Scissors
- A Window or Growing Lamps
- Plastic Wrap
- To illustrate how plants grow faster in greenhouses, have students turn clear plastic pop bottles into planters.
- Cut the top ¼ off of the pop bottle or place it on its side and cut a flap out of the middle of the pop bottle.
- Poke drainage holes in the bottom of the pop bottle (If the pop bottle had a flap cut in it vertically, then the new bottom of the pop bottle is directly below the flap).
- Fill the pop bottle a third to a half full of potting soil.
- Plant two seed in the pop bottle planter.
- Water the seeds.
- Secure the flap or lid with tape or cover the hole with plastic wrap. Poke a few holes in the lid for the circulation of air. You will need to open the lid for daily watering.
- Place the pop bottle planter in a window or under a lamp.
- For comparative purposes, poke some drainage holes in the bottom of a plastic cup.
- Fill the cup ¾ full of soil.
- Plant two of the same seeds in the cup.
- Water the seeds and place them beside the pop bottle planter.
Which seeds do you think will grow fastest? Why?
Have students set-up a daily log to record the growth of the pop bottle seeds and the seeds in the cup.
A Cautionary Note
For younger children, prepare the holes in the pop bottles and cups in advance so that they do not injure themselves with the scissors or exacto knife. If you are doing a class set with younger children, you may wish to send parents a note home asking them to prepare the pop bottle and cup for their child prior to the class with instructions on where to cut the pop bottle. With older students, demonstrate how to cut the pop bottle for them and emphasize caution and safety as they proceed in this task.
The Greenhouse Effect is the effect produced as greenhouse gases allow incoming solar radiation to pass through the Earth’s atmosphere, but prevent most of the outgoing infrared radiation from the surface and lower atmosphere from escaping into outer space.
This effect operates using the same principles as a greenhouse. The Sun’s rays pass through the glass of a greenhouse, but once inside they are trapped, unable to escape the inside of the greenhouse. This trapped light energy causes the greenhouse to heat up, despite its lack of insulation.
So basically the Earth is a greenhouse too – only instead of glass it has an atmosphere that traps the light energy in, warming up the Earth.
The atmosphere is the mixture of gases that surround the Earth. It is composed of nitrogen, oxygen, carbon dioxide, and trace amounts of other gases. The atmosphere is composed of three layers according to its chemical composition and temperature. Closest to the Earth is the troposphere, then the stratosphere, and finally the mesosphere. The greenhouse gases – that act like the glass – are the gases that absorb the infrared light, keeping it in the atmosphere. These include water vapor, carbon dioxide, methane, nitrous oxide, halogenated fluorocarbons, ozone, per fluorinated carbons, and hydro fluorocarbons.
This is a naturally occurring process and without it we could not sustain life as we know it. Without Greenhouse Gases in our atmosphere our planet would be negative 18 degrees Celsius, instead of the current 15 degrees Celsius – 60 degrees Fahrenheit colder.
Activity 2: Man-Made Greenhouse Gases
- A Clear Plastic Pop Bottle with the Top ¼ Cut Off
- Lids and Top ¼ of the Pop Bottle or Plastic Wrap
- Uncut Clear Pop Bottle with it’s Lid
- Dish that Fits the Circumference of the Pop Bottle (possibly a Petri dish)
- Alka-Seltzer Tablet
- 3 Thermometers
- We need greenhouse gases in our atmosphere for life on Earth, so why does everyone talk about greenhouse gases as though they are a bad thing? The problem is that we are releasing additional greenhouse gases in our atmosphere. Discuss man-made greenhouse gases with the students.
- Demonstrate for students how the addition of man-made greenhouse gases to the atmosphere can cause a temperature increase.
- Place a second clear plastic pop bottle beside this pop bottle and place a thermometer inside it. Secure the lid on the pop bottle.
- Finally place a third thermometer on the table beside the two pop bottles.
- Place a desk lamp over the thermometers and turn it on.
- Drop an Alka-Seltzer tablet into the dish of water and cover the pop bottle with plastic wrap or the inverted top 1/4 of the bottle.
- Leave the thermometers alone for at least 20-minutes before checking the temperature.
Which thermometer reached the highest temperature? What do you think caused the difference in the thermometer readings?
- Have students brainstorm ways that they can reduce greenhouse gases at home, play and school.
- Visit a local organization that is successfully reducing greenhouse gas emissions in their workspace or is creating a technology to reduce greenhouse gas emissions. For example, the CK Choi Building at the University of British Columbia is a success story in Sustainable Design. You can read more about it and other University of British Columbia sustainability initiatives at: Sustain.UBC.ca
- Have students brainstorm and set up a project within the school to reduce greenhouse gases. Ideas:
- establishing and managing a school-wide recycling program
- establishing and managing a school-wide composting program
- writing a sustainable column in the school newsletter or on the school web site, educating the school community about what they can do to reduce greenhouse gas emissions
- create a presentation to give at an assembly or to other classes on educating the school community about what they can do to reduce greenhouse gas emissions
- clean up and restore a natural habitat
Without greenhouse gases, we wouldn’t be alive, so why does everyone talk about greenhouse gases like they’re bad? Naturally occurring greenhouse gases are good – we need them to survive. The problem is that humans are releasing additional greenhouse gases in to our atmosphere.
Over the last hundred years, the Earth has warmed an average of 0.6°C or 1°F. Climatologists – scientists that study the climate – think this is the result of man-made greenhouse gases. These are caused by burning fossil fuels and increasing populations. This means more people are releasing greenhouse gases from using cars, electricity, air conditioning, the methane released from our landfills and our farm animals tooting. And to further add to the greenhouse gas, trees that breathe in carbon dioxide are being cut down in large numbers.
If you have any questions about these activities, please us at firstname.lastname@example.org.