Grade 7 ELA - Listen_Interpret (FIAB)

What Causes Thunder?

Listen to the presentation. Then answer the questions.

In the following presentation you will learn about what causes thunder. What causes the sound of thunder? Thunder is caused by the rapid expansion of the air surrounding the path of a lightning bolt. From the clouds to a nearby tree or roof, a lightning bolt takes only a few thousandths of a second to split through the air. The loud thunder that follows the lightning bolt is commonly said to come from the bolt itself. However, the grumbles and growls we hear in thunderstorms actually come from the rapid expansion of the air surrounding the lightning bolt. As lightning connects to the ground from the clouds, a second stroke of lightning will return from the ground to the clouds, following the same channel as the first strike. The heat from the electricity of this return stroke raises the temperature of the surrounding air to around 27,000 C (48,632 F). Since the lightning takes so little time to go from point A to point B, the heated air has no time to expand. The compressed air explodes outward from the channel, forming a shock wave of compressed particles in every direction. Like an explosion, the rapidly expanding waves of compressed air create a loud, booming burst of noise.

"What Causes Thunder?" from http://www.loc.gov/rr/scitech/mysteries/thunder.html. In the public domain.

Hydration Basics for Kids

Listen to the presentation. Then answer the questions.

In the following presentation you will hear a speaker discuss the topic of hydration. Listen to the presentation and then answer the questions that follow.

Ever notice how lifeless a house plant looks when you forget to water it? Just a little water and it seems to perk back up. Water is just as essential for our bodies because it is in every cell, tissue, and organ in your body. That's why getting enough water every day is important for your health. Healthy people meet their fluid needs by drinking when thirsty and drinking fluids with meals. But, if you're outside in hot weather for most of the day or doing vigorous physical activity, you'll need to make an effort to drink more fluids. Most of your water needs are met through the water and beverages you drink. You can get some fluid through the foods you eat. For example, broth soups and other foods that are 85% to 95% water such as celery, tomatoes, oranges, and melons. You need water to replace what your body loses through normal everyday functions. Of course, you lose water when you go to the bathroom or sweat, but you even lose small amounts of water when you exhale. You need to replace this lost water to prevent dehydration.

Excerpt from Hydration Basics for Kids by the Centers for Disease Control and Prevention. In the public domain.