The overall objective of this activity is to discover the best practical shielding material when dealing with radioactive substances. The student will observe, collect, and record data using different sources of shielding materials. The students will be asked to draw conclusions based on availability of materials, price, and best shielding properties.

• Students will demonstrate understanding of the scientific method.
• Students will observe, record, and analyze data.
• Students will use self-directed learning.
• Students will show results on a computer generated graph.
• Students will draw conclusions based on their data showing the relationship of the radioactive materials to the properties of the shielding materials.

__Geiger counter
__Radioactive Source
__Periodic Table of the Elements
__Shielding materials such as: aluminum, steel, tin, paper, wood, brick, glass, plastic, foam, lead, water (shielding materials 
    should be the same length and width)
__Science experiment form (to show steps of the scientific method they will use in the activity)
__Data collection sheet
__Timing device

Preparation:

1. The students will research what a Geiger counter is and what it is used for.
2. The students will investigate the areas of science that radiation is used or could be a problem.
3. Introduce to the students the Geiger counter, some radioactive materials, and the safe handling of materials.

Classroom management:
Divide the students into groups of 4. Three could work, but five is not suggested. Each student has a specific job-- recorder (records all information), reporter (reports all information), materials manager (in charge of all materials and directs clean-up), technical advisor (reads instructions, and follows through, this person is the only one in the group that is allowed to ask the teacher a question).

Questions to Investigate:

1. Ask students if they ever had an X-ray taken.

2. What precautions were taken to shield their bodies and the technicians' bodies from the radiation?

Data Collection:

1. The group should select five shield materials to test.
2. The group will test each shield material by measuring the mR/min.
3. Each shield material should be tested five times for the same time interval each trial (see teaching suggestions).
4. The time intervals for testing periods are .5, 1, 2 and 5 minutes. Students should record the data on the data collection sheet.

Calculations:

1. After performing five tests, an average needs to be taken for that material.
2. This average will be used to construct the graph on the computer.

Communicate results:

• Is there a relationship between the type of material and the mR/min.?
• Compare the similarities/differences with other groups' rates for some of the different materials.
• Possible suggestions for presentations include a poster project, videotape of the experiment using a science format such as, Bill Nye or Beakman's World, Hyper Studio stack, a computer-generated slide show i.e. Claris works or Kid Pix) or an "in-person" demonstration.     

Individual student papers will be judged upon:

• the extent of the literature search.
• clarity of expression.
• practicality of choice of materials (expense, availability, etc.).
• supporting evidence for choice of method, citing conclusions from laboratory activity.

The group will be judged upon:

• the proper use of the Geiger tube.
• the thought put into developing questions and procedures for testing the questions.
• the work as a team.
• the quality of the data and graphs produced
• the effective communication of the results.

• Special care must be taken when handling radioactive materials.
• Make sure students understand the proper operation of equipment. A demonstration would be helpful.
• Students are given a choice as to the time interval they may test the materials. Five minutes would be optimal, however, class time dictates less. Two minutes would be your next best choice. One minute is okay, but .5 should not be used for this experiment at all. You could demonstrate how the readings vary too much with the .5 interval. Try to steer them toward 2 or 5 minutes, depending upon your lesson plans.

Students could select up to three materials, use a one-minute interval and vary the distance from the Geiger counter to see if distance affects the amount of radiation. Discuss nuclear power plants and safety procedures for shielding and handling of radioactive materials. Also, discuss possible environmental hazards, such as polluted water, air, soil. Health risks are also interesting to students, particularly regarding mutations and genetics.