When I'm presenting, I share a variety of ideas for working with multiple texts to increase rigor. It's more rigorous for students to work with two texts to analyze and compare than it is to simply summarize or analyze one. For example, in a social studies class, students might work with a primary and a secondary source. Or students might compare a fiction and non-fiction work, such as The Watsons Go To Birmingham with an article about how Birmingham has changed since the Civil Rights Era.
Another way to use texts is to differentiate through leveled texts. Let's say you have some students who can't read the grade level text. In the strategy Layering Meaning, you find an article or text on the same topic written at an easier level. Then, you have students read that first. Next, they come back to the grade level text. With your support, they read it. Because they have built vocabulary and prior knowledge with the easier text, they are better prepared to deal with the grade level text.
The question is, how do you find the leveled text? Here's a great blog entry from Larry Ferlazzo giving examples of sources for leveled texts. Although one has an optional charge, the rest are free. This provides you exactly what you need for Layering Meaning.