Look at these details from a paragraph about the signs of a tornado.

• 1) Before a tornado, the sky may turn very dark and sometimes green.

• 2) When a tornado is near, you may hear a loud roaring sound that lasts a long time.

• 3) There can be hail or very heavy rain before a tornado strikes.

Choose the main, or central, idea that ties all the details together.

Look at these details from a paragraph about positive and negative effects of flooding.

• 1) Floodwaters can add nutrients to the soil, improving the land for crops.

• 2) The extra water from floods can help some plants grow more quickly.

• 3) On the other hand, floodwaters can carry dangerous diseases.

Choose the main, or central, idea that ties all the details together.

Look at these details from a paragraph about the benefits of deep breathing.

• 1) Deep breathing can lower your stress level and heart rate.

• 2) You can feel more relaxed after deep breathing.

• 3) Practicing deep breathing helps keep your muscles healthy.

Choose the main, or central, idea that ties all the details together.

Look at these details from a paragraph about the positive effects of reading.

• 1) Reading a book before bed can help you relax and fall asleep more easily.

• 2) You can learn new information about various subjects by reading nonfiction books.

• 3) The more you read, the more vocabulary words you will learn.

Choose the main, or central, idea that ties all the details together.

Human Activity and Earthquakes

When Americans think of earthquakes, they tend to think of California, a state known for its frequent seismic activity. In recent years, however, people in Arkansas, Colorado, Kansas, New Mexico, Oklahoma, and Texas have been feeling the ground shake more often. An increase in oil and gas drilling in these states has led to "human-induced" earthquakes—those resulting from human activity. When wastewater is disposed of during gas and oil drilling, the water is forced deep underground. The resulting buildup of pressure can cause fault lines (cracks in the Earth's crust) to shift. According to Mark Petersen, head of the U.S. Geological Survey's earthquake hazard mapping project, "In the past five years, the USGS has documented high shaking and damage in areas of these six states, mostly from induced earthquakes."

What is the main, or central, idea of the passage?

Making Towers Bird-Friendly

The lights on tall communication towers warn pilots to avoid the towers when flying at night. Unfortunately, the steady red lights often used on towers have the opposite effect on birds: the bright beams attract and confuse them. Instead of avoiding the lights, the birds fly directly toward them, crashing into the towers or becoming entangled in power lines. Millions of birds have died this way. However, there is a solution. Unlike steady lights, flashing or blinking lights don't attract birds. In response to demands from conservation groups, the Federal Aviation Administration in 2016 began requiring communication towers in the U.S. to use blinking lights instead of steady ones.

What is the main, or central, idea of the passage?

The Importance of Japan's Cherry Blossoms

In the northeastern United States, autumn is particularly colorful. Leaves change from green to red and orange, and many Americans take scenic fall foliage trips. In Japan, a similar phenomenon takes place in the spring. Cherry trees erupt in a shower of pink, and the entire country celebrates the arrival of sakura, or cherry blossoms. Though autumn leaves are admired in the United States, they are seen as just a pretty seasonal display. In Japan, on the other hand, cherry blossoms have much greater significance; the flowers are deeply rooted in Japan's culture and philosophy. Since as far back as the eighth century, sakura have symbolized change and beauty, new beginnings, and the circle of life. The blossoms have been celebrated in Japanese paintings, poems, and tea ceremonies for centuries.

What is the main, or central, idea of the passage?

In the late 1800s there was a race to invent the "horseless carriage." . . . Coal was too heavy to use for fuel, so people tried other things, including natural gas, gunpowder, and something we now think of as modern: batteries. For a while, batteries seemed to be the answer—by 1897 New York City had a fleet of electric taxis, and in 1899 the world land-speed record of 68 miles per hour (109 kilometers per hour) was set in an electric car. But the batteries were heavy and cumbersome relative to the power they supplied, and they burned out if you tried to go too fast.

Select the best evidence to support the statement that the first electric cars had several drawbacks.

At the turn of the twentieth century, short stories were a preferred form of entertainment in the United States. This was a boom time for magazine publishing, owing in part to developments in offset printing technology as well as to the Postal Act of 1879, which had granted magazines discounted mailing rates. Publications such as Ladies' Home Journal, The Saturday Evening Post, and The Delineator, all of which published short stories, sold more than a half million copies per issue. The authors of these stories were well known at the time and often well paid.

Select the best evidence to support the statement that in the late 1800s, a law made it easier for magazine companies to do business.