The reading discusses some physical science concepts, notably ultraviolet radiation, how it fits into the larger scheme of the electromagnetic spectrum, and how radiation can be absorbed by molecules.

But more important are the concepts of scientific thought that this reading reinforces. The reading is a discussion of measurement. To measure ozone, scientists measure the transmission of UVA radiation, which is not absorbed by ozone. This provides a baseline, telling us how much UV radiation is reaching the earth from the sun. Scientists then measure how much UVC (which is absorbed by ozone) passes through the atmosphere. By comparing UVC levels to UVA levels, scientists can determine how much ozone is in the atmosphere. The concept of using a standards in measurement is reinforced by this understanding. Also important is the concept of inference. Dobson spectrometry never actually observes ozone directly, but only infers its presence or absence from the amount to UVC reaching the earth. Students should understand that inference of this sort is vital to practicing science.

Relevant National Science Education Standards

Unifying Concepts and Processes — The reading describes how some of the evidence is obtained which tells us ozone loss is occurring. The reading also discusses important aspects of scientific measurement, specifically the use of a standard to compare unknowns. In this instance that means using the transmission of UVA by the atmosphere as a standard against which to measure the transmission of UVC, which in turn reveals atmospheric ozone levels.

Physical Science — The reading deals measurement of ozone levels and with the interaction of energy (UV radiation) with ozone in the earth's atmosphere.

Earth and Space Science — The reading deals energy in the earth system in the form of solar UV radiation interacting with the atmosphere.

Science in Personal and Social Perspectives — The reading involves an environmental quality issue which is also a human-induced health hazard, plus the use of science in overcoming this global challenge.

Next: How Do We Measure Tiny Amounts?