Why Does My Child Study but Still Do Poorly on Tests? The Forgetting Curve Explained

Every fall I hear some version of the same story from parents. “She studied for hours. She knew it the night before. Then she sat down to write the test, and it was just gone.”

If you’ve watched this happen with your child, I want you to know that many parents worry about how easily their child forgets what they learn. And once you understand why your child forgets what they study, you can help them use study strategies designed for their brain.

Most of the time, a child who studies hard and still does poorly on tests isn’t lacking effort or ability. They’re up against the forgetting curve, the natural way the brain lets go of information it doesn’t revisit. The good news is that the right study strategies can change that.

How Memory Is Built: We Literally Grow New Pathways

Your brain has roughly 86 billion neurons, and each one reaches out to others through tiny branches. The point where two neurons meet is called a synapse. When your child learns something new, a group of neurons fires together and forms a connection.

At first, that connection is faint. Each time the information is used again, the signal travels more easily, and the pathway gets stronger. The psychologist Donald Hebb described it in a phrase scientists still use today: neurons that fire together, wire together.

It’s no accident that we talk about learning this way. We say “I made a connection” or “that idea really connected for me.” That’s exactly what is happening inside the brain.

Memory is not a recording of what we learned. It is a network of neural pathways that gets stronger every time we use it.

I like to think of it as walking through a field of tall grass. The first time you cross, you barely leave a trace. Walk the same route every day, and it becomes a trail you can follow without thinking.

Forgetting Is Not the Opposite of Memory

Most of us think of forgetting as a failure. But forgetting is its own cognitive function, and the brain does it on purpose. Researchers now understand that the brain actively clears away connections it isn’t using.

Imagine remembering every license plate you ever passed, every lunch you ever ate, and every word of every lecture. You wouldn’t be able to think. You’d be buried in detail with no way to pull out what matters.

Forgetting is the brain’s filtering system. It clears away what we don’t use so we have room to learn what we do.

That’s why we couldn’t learn without it. Your child’s brain is constantly deciding what to keep, and it does so in a surprisingly simple way. If we revisit something, the brain treats it as important.

What Is the Forgetting Curve?

In the 1880s, a German psychologist named Hermann Ebbinghaus memorized lists of nonsense syllables and tested himself at different intervals. Within about an hour, he had lost roughly half of what he learned, and within a day or two, most of it was gone. When he plotted his results, he got a steep downward slope that eventually levelled off. We call it the forgetting curve. More than a century later, researchers repeated his experiment and got results very close to his.

Here’s the part I teach my students. Every time Ebbinghaus reviewed the material, the curve got flatter. The information lasted longer and took less effort to bring back. Research on spaced practice has confirmed this again and again over the past century.

So, when a student hears a lesson on Monday and doesn’t look at it again until the test two weeks later, they aren’t reviewing. They’re relearning from scratch. That’s not a motivation problem or an intelligence problem. It’s a timing problem, and it’s why so many students study hard and still do poorly on tests.

Where Executive Functioning Comes In

Executive functioning is the set of brain skills that help us plan, organize, start tasks, and manage our time. One core piece is working memory, our ability to hold information in mind and use it in the moment. It’s what lets your child follow a teacher’s explanation while connecting it to what they learned the day before.

When working memory is stretched, less information makes it into long term memory in the first place, so the forgetting curve starts even steeper. This is common for students with ADHD and other learning challenges.

But executive functioning also helps us move forward. Noticing that something isn’t sticking, choosing a better approach, and planning when to review are executive functioning skills too.

Study strategies are how students use their executive functioning to work with the forgetting curve instead of losing to it. 

A student who knows they will forget and plans for it will do better on test day.

What This Looks Like for a Real Student

Noah was in grade 11 when his mom reached out. He was bright, and he worked hard, but his chemistry tests kept going badly. He would study for hours the night before, feel ready, and then blank. By the time we met, he had started saying he “just wasn’t a science person.”

We didn’t add more study time. We changed his study strategy. After each class, Noah spent about ten minutes reviewing his notes and creating review questions. He looked at those questions again two days later, and once more at the end of the week. By the time the next test came around, he wasn’t cramming new material. He was remembering it.

His marks went up, but the change I noticed most was in how he talked about himself. He stopped saying he was bad at science and started saying he knew how to study for it.

If this sounds like your child, I’d love to talk. Book a free exploratory call, and we will figure out what’s getting in the way.

Frequently Asked Questions

How often should my child review their notes?

A good starting rhythm is a short review the same day, and then at the end of the week. Short, spaced sessions work far better than one long session the night before.

Does the forgetting curve affect students with ADHD differently?

Everyone forgets, but students with ADHD often face two extra hurdles. Attention differences can mean information is never fully taken in the first time, and executive functioning challenges make consistent review harder to keep up. That’s why structure and support matter so much for these students.

Andrea Zians is an academic coach, learning strategist, and educational consultant at Andrea Zians | Strategic Academics.