Reading comprehension is composed of two equally important components. Decoding, or the ability to translate text into speech, is only part of the process of reading comprehension. The other part is language comprehension, or the ability to understand spoken language. All struggling readers have difficulty with either language comprehension or decoding or both.
Reading comprehension assessments are the most common type of published reading test that is available. And the most typical type of reading comprehension assessment involves asking a child to read a passage of text that is leveled appropriately for the child's age or grade, and then asking some explicit, detailed questions about the content of the text (often these are called Informal Reading Inventories, or IRIs). While there are very many published IRIs, often teachers construct their own and use them to determine the appropriate instructional level for each child.
There are some variations on the basic reading comprehension assessment. For example, instead of explicit questions about facts directly presented in the text, the child could be asked to answer inferential questions about information which was implied by the text, or the child might be asked to retell the story in the child's own words or to summarize the main idea or the moral of the story. Another common reading comprehension assessment is called a "cloze" task - words are omitted from the passage, and the child is asked to fill in the blanks with appropriate words. Also, young children's reading comprehension can be assessed by asking them to read and follow simple instructions, such as, "Stand up" or, "Go look out the window."
Reading comprehension should not be confused with reading accuracy, another very common form of early reading assessment. In a reading accuracy assessment, a child is asked to read a passage of text clearly, without making any mistakes. The mistakes that the child does make are analyzed to find clues about the child's decoding strategies (not reading comprehension strategies). Very often, teachers attempt to assess a child's reading comprehension with a combination decoding/reading comprehension task - the child reads a passage out loud while the teacher makes note of errors the child makes (sometimes called a "running record"), and then the child is asked some comprehension questions about the passage.
This assessment strategy has some problems; children's reading comprehension often suffers when they are asked to read a passage of text out loud. When children read orally, they usually concentrate on reading accurately, and do not pay as much attention to comprehension of the content. Oral reading accuracy does give insights into decoding skills and strategies, but that is a separate test. A reading comprehension test is most accurate if the child is not reading aloud for an audience.
Reading comprehension assessments in this country are almost always written in English. The rare assessments that do exist for second language learners are almost always in Spanish. Because it is very important that children's reading comprehension skills be assessed in both English and in the child's primary language, whatever that language may be, teachers must be creative and resourceful to find or create assessments that they can use with all of their children. Many children who are not proficient speakers of English have substantial literacy skills in their primary language, and teachers should endeavor to assess those skills and build upon them.