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The Science of Reading: What is prior knowledge and why is it important?

Alyssa Buccella

by Alyssa Buccella

February 24, 2022
The Science of Reading: What is prior knowledge and why is it important?

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Posted in: Aha! Blog > Wit & Wisdom Blog > Wit & Wisdom > The Science of Reading: What is prior knowledge and why is it important?

Dr. Hollis Scarborough’s Reading Rope famously shows us that reading is one of the most complex things that we do on a routine basis. Skilled reading requires fluent and coordinated execution of both word recognition and language comprehension but viewing these components as a set of discrete skills to be mastered misses the central role that prior knowledge plays in the reading process.

Scarboroughs Rope

(Image courtesy Dr. Hollis Scarborough, 2001)

The known words, lived experiences, and concepts we have about the world are vital resources for reading and learning. In fact, numerous studies show that background knowledge affects students’ reading comprehension, memory, fluency, and reading speed.

  • Reading Recall and Comprehension
    In 1988, Donna Recht and Lauren Leslie published the landmark “baseball study.” For this study, they had students in grades 7 and 8 read a text about a baseball game and then use an 18-by-20-inch replica of a baseball field (complete with four-inch wooden figures) to reenact the action from the story. Recht and Leslie found that knowledge of baseball had a greater impact than reading ability on how well kids understood the story. As shown in the data below, students with low reading skill did as well as those with high reading skill if they already knew a lot about baseball.

Reading Ability Chart

The Y-axis represents the number of correct movements that students made during story reenactment (one measure of comprehension of the text) Source: (Recht and Leslie, 1988, 18)

With the baseball study, Recht and Leslie helped lay a foundation for decades of additional research in the field. In 2021, a systematic review of 23 studies that focused on the links between background knowledge and reading comprehension consistently found that children with more background knowledge could better comprehend texts. The researchers found that “readers who have strong knowledge of a particular topic, both in terms of quantity and quality of knowledge, are more able to comprehend a text than a similarly cohesive text for which they lack background knowledge. This was evident for both skilled and low skilled readers” (Smith, Snow, Serry, and Hammond 2021).
  • Reading Fluency and Speed
    Background knowledge also influences the speed of our cognitive processing and fluency while reading. In one study, researchers had subjects read a text about four common diseases—like the flu—where participants were already familiar with the symptoms and then read a text about four uncommon diseases—like typhus— where they were unfamiliar with the symptoms. Using technology to track people’s eye movements while they read each text, the researchers found that participants were more likely to reread parts of sentences and look back to previous sentences along the way while reading the unfamiliar text. In other words, readers’ speed and processing slowed as they searched for connections and meaning in the text (Willingham 2006).
In 2011, another study looked at oral reading errors in grade 4 readers with above- and below-average decoding skills, when they either had or lacked prior knowledge of the passage topic. The study found that prior knowledge of the passage topic significantly increased reading fluency and reduced reading errors for less-skilled readers, especially errors based on graphic information (Priebe, Keenan, and Miller 2011).

Research tells us that knowledge plays an important role in becoming a proficient reader. Let’s take a look at how this plays out in many classrooms.

Dispelling Two Major Myths About Prior Knowledge

Readers can use three types of connections to a text to help them understand and remember it: text to text (making connections between a text and other texts), text to self (making connections between a text and lived experiences), and text to world (making connections between a text and events in the world) (Morrison and Wheeler). “Activating” these connections is one of the seven cognitive strategies that highly effective readers use when they read (McEwan 2005), and most teachers have at least heard about the value of activating prior knowledge as part of the reading process.

What does activating knowledge tend to look like in the classroom? Before students read a new text, teachers may prime them to recall related knowledge with concept maps; Know, Want to Know, Learned (KWL) charts; brainstorming; or anticipation guides. But activating prior knowledge assumes a student already has the background knowledge needed to engage with the new content in the first place. It’s common to see some students readily filling in their KWL chart and sharing what they know while others try to piece together what they need to know to successfully read and understand the new material.

“People need to have enough facts in their heads to have what one commentator has called ‘a knowledge party’—a bunch of accumulated associations that will enable them to absorb, retain, and analyze new information.”

—Natalie Wexler (2019, 31)


Activating knowledge is not the same as building it. For all students to become proficient readers, we must dispel two commonly held myths about knowledge in the classroom.

  • Myth 1: Building comprehension skills and strategies is more important than building knowledge. Typically, activating prior knowledge is treated as just one of many strategies that can be taught to and modeled for students, especially less proficient readers, to help them construct meaning from any text they come across. But research shows that background knowledge both significantly influences comprehension and the acquisition and use of other reading comprehension skills.

    In one 2007 study, researchers found that background knowledge, inferences, reading comprehension strategies, vocabulary, and word reading explained 66 percent of the variance in students’ reading comprehension. Of those five variables, background knowledge and vocabulary were the strongest predictors of comprehension. The researchers also found that background knowledge and vocabulary indirectly influenced whether a student would problem solve and apply other reading comprehension strategies when they are having trouble understanding a text (Cromley and Azevedo 2007).

    Natalie Wexler similarly highlights that “the comprehension strategies endorsed by the [National Reading] Panel all rely on activating prior knowledge—which means they only work if a reader has enough background knowledge to understand the text in the first place” (2019b). For example, take another reading comprehension strategy: inferring. Making inferences requires readers to bring together what is written in the text, what is unwritten, and what they already know. It would be hard (perhaps impossible) for a student to accurately make inferences about a text without the background knowledge needed to recognize and then fill gaps about what is written on the page.
  • Myth 2: Students are naturally exposed to the background knowledge they need in the classroom. All students bring different amounts and types of factual, cultural, and social knowledge into the classroom, and the more knowledge a child starts with, the more knowledge they are likely to gain over time. Experts say we need to know the meaning of 90 percent of the words in a text to understand it as well as to learn the other 10 percent of unknown words and build new knowledge. This means that disadvantaged children may not only struggle to understand one text; they are also prevented from expanding their vocabulary and knowledge for future texts they may read. As a result, the gap between advantaged and disadvantaged students can continually grow with each reading experience (Hirsch 2003, 16).

    Here are some of the factors that may influence the background knowledge a student brings to the texts in their classroom:

    • Home environment: In a 2019 study, researchers estimated that the average children’s book contains 140–228 words, and preschool-age kids who have just one picture book read to them per day are exposed to an estimated 78,000 words each year. This means that over the five years before entering kindergarten, students living in literacy-rich home environments hear an estimated 1.4 million more words than children who are never read to (Logan et al. 2019).

    • Family income: In one study, four-year-olds from low socioeconomic status (SES) families demonstrated less background knowledge about birds than their middle-SES peers and had more difficultly comprehending an 18-page picture book about four types of birds. However, when the researchers held background knowledge constant by creating a similar 18-page book introducing a made-up topic—“wugs”—that was unknown to both groups of children, there were no significant differences between the children’s word learning, comprehension, or ability to make inferences (Kaefer, Neuman, and Pinkham 2014).

    • Cultural background: Studies show that cultural context also influences students’ reading comprehension. For example, one study on cross-cultural comprehension had participants from the US and India read letters about an American and an Indian wedding. Researchers found that study participants read the passage faster, recalled more information, and produced more culturally appropriate elaborations of the content when reading about their own culture (Robertson 2007).

    • Prior instruction: Elementary schools spend far more time on ELA instruction than on science and social studies. Often, the hope is that students will strengthen abstract reading skills that will help them make meaning of subject- specific texts in later grades. But without intentional scaffolding of subject- specific vocabulary and concepts in early grades, students may lack the prior knowledge needed to access complex technical concepts in later grades.

      In fact, research finds that students with an integrated science and literacy curriculum make greater gains in science and literacy learning (Cervetti et al. 2012). And in 2020, another study found that students who received an additional 30 minutes of daily social studies instruction in grades 1 through 5 scored higher on reading exams by the end of grade 5 (Tyner and Kabourek).

The research is clear: Building student background knowledge is integral to reading comprehension and is an equity imperative. So how can you embrace knowledge building in your own classroom?

Build Student Knowledge Now: Three Knowledge-Building Practices to Support Your Literacy Instruction

Providing some context and identifying common terms before having students read a text are important but building student knowledge is not just about drilling vocabulary. As Susan Neuman, Tanya Kaefer, and Ashley Pinkham explain, “Knowledge is not just accumulating facts; rather, children need to develop knowledge networks, comp[o]sed of clusters of concepts that are coherent, generative, and supportive of future learning in a domain” (2014).

Here are three ways you can shift your practice toward more effective knowledge building, with the goal of cultivating in students a broad and deep base of content knowledge that will set them up for success.

  1. Use text sets and encourage topic-focused wide reading.

    Current practice: Curricular materials, like basal readers, jump around to different themes across a day or week as they focus on teaching and reinforcing reading skills. In addition, students are encouraged to read often and widely, usually taken to mean that they should read a lot of different books and about a variety of topics.

    Research in action: Word learning occurs up to four times faster when the verbal context is familiar (Hirsch 2006). Instead of having students read about baseball one day and the moon the next, stick with a single theme or topic like sports, the seasons, the sea, or outer space for several weeks at a time. This will allow words and concepts to strategically recur with greater depth of meaning and complexity over time.

    A deep dive into outer space, for example, may include a collection of texts in a variety of genres and formats—fiction, nonfiction, picture books, poetry, videos, articles— that systematically expose students to information about the moon and stars, space exploration, and how our understanding of space has changed over time.
    Outer Space Books
    Providing opportunities for students to experience the same topic over an extended period allows them to expand their vocabulary, make connections within and between texts, and not only broaden but deepen their body of knowledge and transfer it to new contexts.

  2. Integrate ELA instruction with content areas like social studies, science, and art.

    Current practice: ELA instruction crowds out instructional time spent on other subjects like science and social studies in an effort to improve reading skills and achievement, and ELA curriculum materials are not intentionally connected to those other content areas.

    Research in action: ELA instruction is not just an opportunity to build students’ literacy skills and general vocabulary. It is an opportunity to systematically build their knowledge of the world. Integrating reading instruction with other subject areas helps students build an integrated body of knowledge that benefits their reading comprehension and lays a foundation for accessing increasingly technical and subject-specific material in later grades. As Natalie Wexler argues in a 2019 interview, “If we really want to boost reading comprehension, we should be doing the opposite of what we’re doing—especially in schools where test scores are low—which is cutting subjects like social studies and science that could actually increase students’ knowledge of the world and instead spending more time on these reading comprehension skills” (Barnum).

    For example, imagine if ELA instruction deeply explored texts and materials about farm life in kindergarten, animal features in first grade, the seasons in second grade, and the ocean in third grade. Students would become well prepared to apply their background knowledge and vocabulary to learn about how animals, weather, and landscapes interact in ecosystems in their science classroom.

    Similarly, aligning ELA texts with social studies topics like the continents, life in the American West, and America’s key conflicts can provide students with the foundation needed to connect to new knowledge and deeper engagement with the Great Depression or World War I in their social studies lessons.

  3. Create ample opportunities for students to listen to and talk about content-rich texts.

    Current practice: Students engage in independent, silent reading at their reading level to build fluency, vocabulary, and comprehension skills.

    Research in action: Listening comprehension outpaces reading comprehension from early childhood through at least middle school (Fisher and Frey 2014). Picture books and read alouds filled with rich content and language allow students to build knowledge by using text that is more complex than text they may be able to read themselves.

    Additionally, when students have regular time to engage in teacher-led and peer-to-peer discussions about complex texts and topics, they deepen their knowledge and comprehension (Ramirez Stukey, Fugnitto, Fraser, and Sawyer). Talking about texts can help students make connections between new and existing knowledge, and discussing open-ended questions before, during, and after reading can help students think through and remember the themes of a text.

Barnum, Matt. 2019. “Want better readers? Spend less time teaching kids to find the main idea, ‘Knowledge Gap’ author Natalie Wexler argues.” Chalkbeat. Sept 16, 2019. http://www.chalkbeat. org/2019/9/16/21108839/want-better-readers-spend-less-time-teaching-kids-to-find-the-main-idea- knowledge-gap-author-natalie.

Cervetti, Gina N., Jacqueline Barber, Rena Dorph, P. David Pearson, and Pete G. Goldschmidt. 2012. “The Impact of an Integrated Approach to Science and Literacy in Elementary School Classrooms.” Journal of Research in Science Teaching 49, no. 5 (April): 631–658.

Cromley, J. G., and R. Azevedo. 2007. “Testing and refining the direct and inferential mediation model of reading comprehension.” Journal of Educational Psychology 99, no. 2 (May): 311–325.

Fisher, Douglas, and Nancy Frey. 2014. “Speaking and Listening in Content Area Learning.” The Reading Teacher 68, no. 1 (Aug): 64–69.

Hirsch, E. D., Jr. 2003. “Reading Comprehension Requires Knowledge—of Words and the World.” American Educator 27, no. 1 (Spring): 10–29.

Hirsch, E. D., Jr. 2006. “The Case for Bringing Content into the Language Arts Block and for a Knowledge-Rich Curriculum Core for all Children.” American Federation of Teachers, (Spring).

Kaefer, Tanya, Susan Neuman, and Ashley Pinkham. 2014. “Pre-Existing Background Knowledge Influences Socioeconomic Differences in Preschoolers’ Word Learning and Comprehension.” Reading Psychology 36, no. 3 (Aug): 203–231.

Logan, Jessica, Laura Justice, Melike Yumus, Johanna Chaparro-Moreno. 2019. “When Children Are Not Read to at Home: The Million Word Gap.” Journal of Developmental and Behavioral Pediatrics 40, no. 5 (June): 383-386.

McEwan, Elaine K. 2005. Seven Strategies of Highly Effective Readers: Using Cognitive Research to Boost K-8 Achievement. Corwin Press.

Morrison, Vanessa, and Lisa Wheeler. “Revisiting Read Alouds: Instructional Strategies that Encourage Students’ Engagement with Text.” Reading Rockets. Accessed Jan 19, 2022.

Neuman, Susan, Tanya Kaefer, and Ashley Pinkham. 2014. “Building Background Knowledge.” International Literacy Association, 68, no. 2 (Sept): 145-148.
Priebe, Sarah K., Janice M. Keenan, and Amanda C. Miller. 2011. “How Prior Knowledge Affects Word Identification and Comprehension,” Reading and Writing 25 (Jul): 581–586, s11145-010-9260-0.

Ramirez Stukey, Marisa, Gina Fugnitto, Valerie Fraser, and Isabel Sawyer. “The Settled Science of Teaching Reading.” Center for the Collaborative Classroom. Accessed Jan 19, 2022. public.cdn.

Recht, Donna R., and Lauren Leslie. 1988. “Effect of Prior Knowledge on Good and Poor Readers’ Memory of Text.” Journal of Educational Psychology 80, no. 1 (March): 16–20,

Robertson, Kristina. 2007. “Connect Students’ Background Knowledge to Content in the ELL Classroom.” Reading Rockets. Accessed Jan 19, 2022.

Smith, Reid, Pamela Snow, Tanya Serry, and Lorraine Hammond. 2021. “The Role of Background Knowledge in Reading Comprehension: A Critical Review.” Reading Psychology 42, no. 3 (Feb): 214–240.

Tyner, Adam, and Sarah Kabourek. 2020. “Social Studies Instruction and Reading Comprehension: Evidence from the Early Childhood Longitudinal Study.” Thomas B. Fordham Institute (September).

Wexler, Natalie. 2019. The Knowledge Gap: The Hidden Cause of America’s Broken Education System—and How to Fix It. New York: Avery, an imprint of Penguin Random House LLC.

Wexler, Natalie. 2019b. “Why We’re Teaching Reading Comprehension in A Way That Doesn’t Work.” Minding the Gap. Willingham, Daniel T. 2006. “How Knowledge Helps: It Speeds and Strengthens Reading Comprehension, Learning—and Thinking.” The American Federation of Teachers (Spring).

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