As schools across the country anxiously await the results of their new Common Core–aligned assessments, there’s one thing I wish all policy makers understood: The reading comprehension tests are valid, reliable, and unfair.
Standards-based assessments mean very different things in reading and math. The math standards include mathematics content—they clearly specify what math knowledge and skills students are supposed to master in each grade. That is not true in reading. The English language arts and literacy standards only specify the skills students are to master. They implore schools to build broad knowledge, but other than a few foundational texts in high school, they don’t indicate what knowledge students need to learn.
In brief, reading comprehension tests primarily assess decoding, fluency, vocabulary, and knowledge. A child who answers a question wrong might be struggling with decoding, or might be a fluent reader who lacks knowledge of the topic in the passage.
Reading comprehension is widely misunderstood as a skill that depends on applying strategies like finding the main idea (assuming fluent decoding). Cognitive science (and common sense) has established that comprehension actually depends on knowledge and vocabulary. If you know about dinosaurs, you can read about them. If you don’t know about a topic and haven’t learned vocabulary related to that topic, you will have to learn about it before comprehending a text on it (e.g., “Chirality plays a fundamental part in the activity of biological molecules and broad classes of chemical reactions, but detecting and quantifying it remains challenging. The spectroscopic methods of choice are usually circular dichroism…”).
If the standards specified what topics children should read about in each grade—and thus what topics may appear in the passages on the reading comprehension tests—then aligned assessments would be better measures of both how the students are progressing and the quality of the instruction they received. Because the standards offer no indication of which topics ought to be studied and thus no indication of which topics might be tested, the assessments are very blunt measures of students’ progress and teachers’ abilities. They are valid and reliable—they do indicate students’ general reading comprehension ability—but they conflate what’s been learned inside and outside school. They’re unfair.
That’s why reading comprehension scores are so strongly correlated with socioeconomic status and so difficult to improve. Comprehension depends on knowledge and vocabulary, but the topics on the test are unpredictable. So, the only way to be well prepared is to have very broad knowledge and a massive vocabulary. From birth, some children are in vocabulary- and knowledge-rich homes, while others are not. Making matters worse, only some children have access to high-quality early childhood education programs and K–12 schools.
Life is unfair, but these tests need not be. States could specify what topics are to be taught across subject areas in each grade and they could mandate that the passages on the reading comprehension assessments draw from those specified topics. In short, states could work toward knowledge equality.

Teach broad knowledge and test what’s been taught. Is that really too much to ask? (Image courtesy of Shutterstock.)