Read Grade-Level Text With Understanding Practice Test

Read the text to learn information about a natural process.

How Ants Find Their Way Home

Have you ever watched a line of ants on a sidewalk and wondered where they are going? Ants often travel far from their nests to find food. The amazing part is that they usually return home without getting lost. This article explains two main tools ants use to navigate.

First, many ants follow scent trails. When an ant finds food, it may leave a thin chemical smell behind it as it walks. Other ants can smell that trail with their antennae and follow it like a path. If the food is good, more ants travel the same route, and the trail becomes stronger. You can sometimes see ants choosing between two leads, which shows they are “reading” different smells.

Second, some ants use the sun and sky to guide them. These ants notice where the sun is and keep track of their turns as they walk. It is like building a map in their minds. Even on cloudy days, certain ants can sense patterns of light in the sky that humans cannot easily see.

Ants also solve problems when their trail breaks. A rain drop, a shoe, or a curious dog can erase part of the scent. When that happens, ants may spread out and search in a looping pattern until they find the trail again. Once one ant reconnects with the path, others follow.

Scientists study ant navigation because it can inspire new technology. For example, some robots are programmed to follow “virtual trails” the way ants follow scent. In the future, these ideas could help robots deliver supplies or explore places that are hard for people to reach.

In short, ants do not rely on luck. They use smell, sunlight, and smart searching to travel safely between food and home.

Read the informational text to learn how a system works.

From River to Tap: How Drinking Water Gets Clean

When you turn on a faucet, clean water seems to appear instantly. But before water reaches your home, it often travels through a treatment plant. The plant’s job is to remove dirt and germs so water is safe to drink.

First, water from a river or lake enters the plant through large screens. These screens catch big items like sticks, leaves, and trash. This step protects the machines farther inside.

Next comes coagulation (koh-AG-yuh-LAY-shun). Workers add a chemical that makes tiny bits of dirt stick together. Those clumps are called flocs. Because flocs are heavier, they can be separated more easily.

Then the water moves slowly through tanks so flocs can settle to the bottom. After that, the water goes through filters made of sand, gravel, or charcoal. Filters trap smaller particles that did not settle.

Finally, the plant disinfects the water to kill germs. Many plants use chlorine, ultraviolet light, or ozone. The water is tested to make sure it meets safety rules before it flows into pipes.

Clean water does not happen by accident. It takes several steps working together, and each step makes the next one more effective.

Question: Why does the author include the steps in order from screens to disinfection?