I find colored pencils or highlighters are so useful when teaching writing. But they can be just as useful when teaching reading, especially if the same colors are used consistently.
Suppose you are teaching students to identify the main idea in a reading passage, and that the students are reading from a source which they can mark. First, have students read a passage. Then help them discover the main idea. Instruct them to underline or highlight the main idea with a particular color, such as red. Later, whenever you are working on main idea, ask students to identify it with a red underline.
Sometimes a whole sentence is a main idea, but sometimes the main idea is not identified so neatly. Sometimes a phrase can be underlined. Or sometimes the student needs to write the main idea over the title using red ink if it is implied but not stated directly.
Many times all or part of the main idea is repeated in paragraph after paragraph. Students need to know that the main idea is often repeated, and they need to identify examples of it by underlining those repeats with their red pencils.
What if you are teaching supporting details? A different color—say orange—could be used to underline supporting details. If the main idea in a Cinderella story is that Cinderella wants to go to the ball, then all the details helping her get there should be underlined in orange—the fairy godmother, the pumpkin carriage, the mice footmen, the ball gown and of course the glass slippers. Even the clock striking is an important detail.
Almost every reading test asks for the main idea. Students need practice, lots of practice in all kinds of reading materials, to identify the main ideas and the details which support the main ideas.
If you are consistent with your color choices, students will get used to seeing their reading through the colors they apply. And if you are checking to see if students are identifying correctly, all you need to do is look for the color red or orange or whatever color scheme you decide on. Walking around a classroom, you can easily tell if the students identify correctly, or if they are fooled.
You might be thinking, but students can’t mark textbooks. True. But so many schools today use workbooks in many subjects for each student. Even if the purpose of a particular passage has nothing to do with finding a main idea—a science or math passage, for example—you can still use it to identify main ideas.