To learn about sources of high-energy radiation and calculate student exposure to ionizing radiation over the past year.
This lesson was developed by the Challenger Center as part of NASA's MESSENGER Mission, of which Science NetLinks is a partner.
Radiation can affect living and mechanical things on earth as well as in space. In the first part of the lesson, students calculate their yearly exposure rate to harmful high-energy radiation and cumulative effects over time. They then use the information to evaluate the various sources of radiation that are of greatest concern for them. In the second part of the lesson, students learn that spacecraft and other objects in space must be concerned with the same kinds of radiation to which humans are exposed. The MESSENGER spacecraft will orbit Mercury and be subjected to much more intense solar radiation than it would near Earth. Students discuss the notion that even though some of the radiation is needed to study the properties of the planet, too much of it can be quite damaging.
Refer to the Science Overview section of the lesson for a summary of the science content relevant to the activities in the lesson. In order to successfully complete this activity, students should already have had some instruction in heat and energy transformations. Refer to the Lesson Overview for a more detailed explanation of what students will learn from the lesson.
Note: Parts of this lesson were extracted from the unit, Staying Cool.
Depending on your time and interest, you may wish to open the lesson using the brief activity in the Additional Warm-Up and Pre-Assessment section of the Lesson Plan, where "radioactive material"—in the form of glitter—is poured on desks. You should then ask students a series of questions about how they think and feel about their exposure to it.
As part of the regular Warm-Up and Pre-Assessment section, have students talk about radiation and review what they know about electromagnetic radiation using a spectrum visual. You also should have them do a number of simple experiments that will demonstrate that the more energy something has, the more the atoms and molecules that form it vibrate. From this standpoint, students then learn about how ionizing radiation gets produced—when rapidly vibrating atoms "break," triggering high levels of energy that can be very harmful to people or things.
To start this lesson, use the four-column chart shown in the Procedures section of the Lesson Plan to see if students can identify different types of radiation, their sources and uses, and determine whether they are harmful to humans. This exercise will help students learn the differences between high- and low-energy radiation and how both can be harmful and beneficial to humans. (See Sample Table on page 50 of the MESSENGER lesson plan to support this activity and discussion.)
Using the Calculating Your Yearly Exposure to Ionizing Radiation student sheet, have pairs of students then estimate their yearly exposure to ionizing radiation. As part of the class discussion on their findings, ask each pair check their exposure rates using the chart on the Likely Effects of Ionizing Radiation for Whole Body Radiation Doses to Individuals student sheet to determine how they can protect themselves. Student understanding can be assessed by passing out the Questions About Radiation Exposure student sheet, which contains a list of comprehension questions based on what they have learned up to this point in the lesson.
Depending on time and preferences, you can discuss the activities in the Discussion and Reflection section in a follow-up lesson or assign them as homework. They include addressing questions on ionizing, solar, and cosmic radiation; learning about the MESSENGER mission and the solar activity cycle using the Questions About MESSENGER and the Solar Activity Cycle student sheet; and reading the MESSENGER Information Sheet and becoming aware of the serious concerns that MESSENGER spacecraft designers have about excessive exposure to solar radiation.
Note: The Answer Key provides answers to questions on the student sheets.
Use the Closing Discussion to focus on the importance of using scientific methodology when studying areas like high-energy radiation. One example: the MESSENGER mission and how decades of research on radiation have enabled humankind to send a spacecraft close to the hostile sun.
You can use the student sheets to further assess student understanding of this lesson. The Assessment section also provides a number of radiation-based essay questions that students can address.
Divide students into two debate teams. Have a debate regarding a possible proposal to build a nuclear plant in their neighborhood. Have participants discuss the social and political implications of the Not In My Back Yard (N.I.M.B.Y) philosophy.
Have students research how radioactive substances are stored. How could radioactive material get into the hands of people who are not qualified to handle it? Have students research the concerns about how radioactive substances from the former Soviet Union might end up in the hands of criminals. Discuss current concerns about the use of radioactive "dirty bombs." Follow the discussion of the storage of nuclear waste in Yucca Mountain in Nevada, and examine how much of the discussion is based on science and how much is politics (such as N.I.M.B.Y).
Have students investigate the history of research on radioactivity. For example, profile Marie Curie, one of the pioneers of the field. Discuss ways in which exploring unknown phenomena can be dangerous; early scientists at first did not know about the dangers of radioactivity and did not protect themselves against it.