Earth's sunscreen – the ozone layer

Activity 2

Correcting false statements

Working in groups of two or three, decide whether the following statements are true or false. Keep a note of your decisions and write out a correct version of the false statements.

  1. Ozone consists of oxygen atoms.
  2. Ozone is poisonous.
  3. Methane destroys the ozone layer.
  4. Chlorofluorocarbons are greenhouse gases.
  5. Ozone concentrations are highest in the troposphere.
  6. Ultraviolet radiation is highest at the equator.
  7. The greatest loss of stratospheric ozone has occurred over the equator.
  8. Atmospheric ozone forms in the darkness of the Antarctic winter.

Teachers notes

  1. True
  2. True
  3. False. A true statement would be: Methane does not destroy the ozone layer. It is a greenhouse gas.
  4. True
  5. False. A true statement would be: Ozone reaches its highest concentration in the stratosphere.
  6. True
  7. False. A true statement would be: The biggest loss of stratospheric ozone has occured over the poles, especially over the southern pole.
  8. False. A true statement would be: Atmospheric ozone forms by the action of ultraviolet radiation on oxygen.

This exercise is valuable because this topic is likely to have been introduced to students via the media and the students may have picked up misconceptions, distortions or incorrect information.

In particular students frequently confuse ozone depletion with the enhanced greenhouse effect. It is important to emphasise that the two effects are completely different.

You could use this activity before beginning the topic to see if students are confused about some aspects.

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Posted February 2007.