Focus on Genre: Organization of Ideas
• Comparison and Contrast
Writers organize texts in a way that will explain facts and ideas effectively. A writer who wants to show how things are alike and different uses comparison-and-contrast organization.
How It Works
To compare things is to show how they are similar. To contrast is to show how they are different. As you read, look for signal words that show similarities and differences.
| Words That Signal Similarities | Words That Signal Differences |
|---|---|
| like | but |
| both | unlike |
| also | although |
| too | different |
| similarly | in contrast |
| just as | on the other hand |
Io is a moon that circles the planet Jupiter. Although Io is a moon and Earth is a planet, the two are alike in some ways. For example, Earth’s oceans have tides. That is, the level of the ocean water along the shore rises and falls regularly, pulled by the moon’s gravity. Like Earth, Io also has tides. But unlike Earth’s ocean tides, Io’s tides are in its solid surface. Io’s solid surface rises and falls, pulled by gravity from the planet Jupiter and two other moons that orbit Jupiter.
Contrast signal words show how Io and Earth are different.
Comparison signal words show similarities between Earth and Io.
While both Earth and Io have active volcanoes, Io has no water and gets no rain. Unlike Earth, Io cannot support life as we know it. In contrast to Io, Earth is a friendly habitat for many kinds of life.
Signal words help readers see that the paragraph begins with a comparison, then continues with contrasts.
Io (left) has a temperature of –230°F. Earth’s most extreme recorded low is –129°F.