Why Background Knowledge Matters in Reading (and How PBL Builds It)

Why Background Knowledge Matters for Reading Comprehension

I have such vivid teaching memories of listening to students read every word fluently, but still look at me with confusion in their eyes when I asked the inevitable follow up question. They were reading, but they were not understanding. 

They were reading, but they were not understanding.

Early in my career, I used to wonder if the problem was motivation, effort, or maybe even attitude. But the more I dug into the Science of Reading, the clearer it became: background knowledge plays a huge role in any reader's comprehension. Without it, even the strongest readers can stumble. This fits with what we know about the importance of word recognition and language comprehension, as described in our version of the Simple View of Reading.

The Baseball Study: How Background Knowledge Impacts Comprehension

One of my favorite pieces of research on the importance of background knowledge comes from the famous “Baseball Study” by Recht and Leslie (1988). In this study, researchers gave middle school students a passage about baseball and then tested their comprehension. Here’s the twist: students with high baseball knowledge (even those who were weaker readers) outperformed students who were strong readers but didn’t know much about baseball.

The takeaway? Decoding skills matter, but comprehension depends heavily on what readers already know. When students don’t have the schema to make sense of a text, their reading ability only takes them so far. As a teacher, that study was a lightbulb moment for me. It confirmed what I had seen again and again: struggling readers often aren’t “bad readers”—they’re readers without the necessary background knowledge for the task at hand.

Struggling readers often aren’t ‘bad readers’—they’re readers without the necessary background knowledge for the task at hand.

Scarborough’s Reading Rope Explained: Where Background Knowledge Fits

If you’ve ever seen Scarborough’s Reading Rope, you know it’s a great visual for understanding how the strands of reading work together. The rope has two big sides: word recognition and language comprehension. Background knowledge falls into the language comprehension side, woven together with vocabulary, verbal reasoning, and knowledge of text structures.

When the background knowledge strand is frayed or thin, the whole rope is weaker. Students may be able to sound out words just fine, but without context, those words don’t braid into meaningful comprehension. That’s why building knowledge isn’t just an “extra” in literacy instruction—it’s essential.

How Project Based Learning (PBL) Builds Background Knowledge

Sometimes teachers worry that their students aren't good enough readers for project-based learning (PBL). But here’s the good news: PBL is one of the best vehicles for strengthening students’ background knowledge, actually helping kids become better readers. Projects naturally immerse kids in a topic, offer multiple entry points into vocabulary and concepts, and help them build knowledge in a way that sticks. If you're intrigued by the relationship between the Science of Reading and Project-Based Learning, we have a whole blog about that specifically. If building background knowledge is your jam though, read on here for some examples across grade levels and content areas.

Elementary Example of Building Background Knowledge

Imagine a second-grade class working on a project about local plants and pollinators. Students read picture books and short informational texts about bees, butterflies, and flowers. They might also watch a video of a pollinator in action, plant seeds in the school garden, or even Zoom with a local beekeeper.

Every one of those experiences layers background knowledge and the words that come with that. So when students later read a more complex article about pollination, they bring a mental model that helps them decode terms like “nectar” or “habitat” and actually understand them.

Middle School Example of Building Background Knowledge

In a middle school social studies project, students might investigate immigration stories from their community. Teachers can build background knowledge by having students examine maps of migration patterns, read oral histories, and interview local families.

When those students later encounter a dense primary source like a historical newspaper article, they’re not coming to it cold. They’ve got enough context to make the reading meaningful.

High School Example of Building Background Knowledge

Back in my own high school ELA classroom, I’ve had students create multimedia projects on dystopian literature and its connections to history. Before they can dive into Orwell or Atwood, they need to understand concepts like totalitarianism, propaganda, and surveillance.

I built this knowledge with short nonfiction texts, podcasts, and even analyses of modern-day advertising. By the time they open 1984, they’re already fluent in the big ideas, which frees up their working memory to focus on analyzing language and theme.

Strategies to Build Background Knowledge in the Classroom

So what can teachers do to intentionally build background knowledge, especially within the flow of projects? Here are a few strategies that work across grade levels and subjects:

• Use multimedia “knowledge builders.” Before a project launches, share short videos, visuals, or even hands-on artifacts. For example, a video of a rocket launch can give students the sensory context they’ll need before reading technical descriptions in a STEM project.

• Frontload vocabulary in context. Instead of just giving definitions, embed new words into the project itself. In a health project on nutrition, students can learn terms like “metabolism” or “nutrient-dense” as they design meal plans for athletes.

• Leverage read-alouds and shared reading. Even in secondary classrooms, reading a short article aloud and stopping to explain context builds shared knowledge. In elementary grades, read-alouds are especially powerful for exposing students to complex ideas they might not yet decode independently.

• Connect to students’ lived experiences. If students are working on a civics project, connect the concept of “representation” to their own school environment before unpacking the Constitution. Making the abstract concrete builds knowledge bridges.

• Spiral knowledge across disciplines. When the science teacher is doing a project on ecosystems, the ELA teacher might assign informational texts or stories about the environment. Students then encounter the concepts in multiple contexts, strengthening both vocabulary and understanding.

• Model curiosity and questioning. Sometimes students don’t even know what they don’t know. During a project on the Industrial Revolution, for example, I might pause and say, “Wait, what’s a textile mill? Let’s look it up together.” Modeling this shows that good readers constantly build knowledge as they go.

• Extend your learning with ready-to-use strategies. We've created a one-page graphic full of ideas for integrating the Science of Reading and Project-Based Learning. You can download it for free from the ACP Store.

Why Background Knowledge Is Essential for Reading Success

If the Baseball Study showed us anything, it’s that knowledge levels the playing field. And Scarborough’s Rope reminds us that reading comprehension isn’t just about decoding—it’s about weaving together multiple strands, with background knowledge as one of the strongest fibers.

Knowledge levels the playing field.

The best part is that building knowledge doesn’t have to feel like “extra work” for teachers or students. In fact, PBL gives us a natural framework for embedding it. Whether it’s second graders growing a garden, eighth graders interviewing local immigrants, or high schoolers analyzing dystopian societies, projects help students accumulate the rich knowledge that makes reading meaningful.

As a teacher, I no longer see blank stares during reading as a lack of effort. More often than not, it’s a lack of context. And that’s something we can give our students—with intention, with creativity, and with a little help from the science of reading.

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