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Key Idea

  • Humans alter the environment on continental and worldwide scales.


In the last section, students learned about the impact of human populations on the environment. This section takes an in-depth look at the ability of humans to affect the environment on a large scale by examining the topics of acid rain and global warming. Students learn how acid rain is formed and the harmful effects of acid rain on the environment. Students also learn about the different gases that contribute to the greenhouse effect. Then they construct a model of Earth and simulate the greenhouse effect and global warming by altering the model's conditions.



\checkmark identify the gases that contribute to acid rain and the greenhouse effect.

\checkmark explain how acid rain is formed and its impact on the environment.

\checkmark explain how greenhouse gases contribute to global warming and its impact on the environment.

\checkmark discuss how they can reduce the current levels of acid rain and greenhouse gases.


acid rain, acidity, CFCs (chlorinated fluorocarbons), global change, global warming, greenhouse effect

Student Materials

Activity 10-1: Feeling the Heat: The Greenhouse Effect

Per student

  • Activity Report
  • Materials may vary.

Per group

  • Glass bowls or containers of various sizes; Lamp; Dirt; Ice; Water; Colored paper; Thermometer

Teacher Materials

Activity 10-1: Feeling the Heat: The Greenhouse Effect

  • Activity Report Answer Key

Advance Preparation

See Activity 10-1 in the Student Edition

Interdisciplinary Connection

Social Studies Students explore environmental issues affected by economics, policies, and cultures.

Background Information

Acidity and Alkalinity Acidity is measured in terms of pH. What makes a liquid acidic is the amount of free hydrogen ions that are floating around. The pH is actually the negative logarithm of the hydrogen ion concentration, [H^+]. The pH scale is a logarithmic scale that runs from 1 to 14. A liquid with a pH of 7 is considered neutral. Those liquids with a pH lower than 7 are acidic and those with a pH higher than 7 are alkaline. Because the pH scale is logarithmic, a liquid with a pH of 6 is ten times more acidic than a liquid with a pH of 7. A liquid with a pH of 5 is 100 times more acidic than one with a pH of 7. Acid rain in the northeastern United States has been measured as having a pH of 3!

Alkalinity is a measure of a liquid's hydroxide ion concentration, [OH^-]. Alkalinity can be measured on a scale similar to pH called pOH. On the pOH scale, a liquid with pOH 7 is neutral. A liquid with pOH lower than 7 is alkaline. A liquid with pOH greater than 7 is acidic. Generally, alkalinity is inversely related to acidity, so it is more common to refer only to acidity.

Chlorinated fluorocarbons (CFCs) CFCs were used as propellants in most aerosol cans until this use was banned in the United States. However, CFCs are still found in some older refrigerators and air conditioners, in making plastic foam for packing and insulation, and as medical sterilizers. Industries are trying to devise economical replacements.

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Date Created:

Feb 23, 2012

Last Modified:

Apr 29, 2014
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