Presenting the task: Each child should have access to drawing tools (pencils, a compass, a ruler). Before passing out the student activity materials, the teacher should conduct a short discussion of lightning, focusing especially on the fact that often you see the flash of lightning before you hear the thunder clap. (Children will probably relate their own experiences of seeing a flash before hearing the rumble.) He or she should explain that the two occur simultaneously, but sound travels more slowly than light. Hence, the thunder is heard after the lightning is seen. In fact, the farther away one is from the flash, the greater is the gap between seeing and hearing. The teacher should describe one way to estimate the distance between someone and a lightning flash: Count the number of seconds between the flash and the thunderclap. That number, divided by five, is approximately the number of miles between the person and the lightning.

The teacher also can discuss safety-related issues as appropriate.

Student assessment activity: The teacher should pass out the student sheets and read the introduction as the class follows along. Discuss questions 1 and 2 as a group to be sure that the students understand the general concepts involved. The students should select tools (ruler, compass, calculator) that are appropriate to the task as they need them.

Note: if the student materials are duplicated from this book, the scale may be affected. If necessary, the teacher should redraw the figure ensuring that the distance from point E to point B on the map is 2 inches. The same map can be used without the lightning in questions 5 through 8.



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