Why Do Students Forget What They Have Learned? Busting the “They’re Just Not Trying” Myth

You watch them sit at the table, furrowed brow, pencil tapping… and somehow, by next week, it’s like that whole math lesson never happened.
It’s frustrating.
It’s confusing.
And it’s definitely not about laziness or lack of effort.

I remember handing my high school chemistry teacher a blank quiz sheet.
My mind had completely blanked out.
Just two days before, I had practiced similar problems and done fine.
Ordinarily, I could look at the information, figure out what to do, and go from there—but not this time.
Class had just ended. In resignation, I walked up to her desk and handed her the blank sheet.
She looked at me, shrugged, and took the paper.
I walked out thinking, Memory… you failed me again.

So many parents and students are left wondering why do students forget what they have learned, especially when it seemed like they understood it the day before.
The biggest myth?

“They just aren’t trying hard enough.”

The truth is: your child’s brain might be doing exactly what it’s built to do—but we have to understand how it works, especially when neurodivergence comes into play.

🧠 How the Brain Decides What’s Worth Remembering

Our brains are survival machines.
It prioritizes anything that feels important to our safety, security, or social standing (LeDoux, 2012).

For kids, especially those still developing cognitively, this means their brain filters every piece of information and asks:

“Is this going to help me survive socially or physically?”

That’s why your child might forget how to divide fractions…
…but can instantly remember a joke their friend told them at lunch, or what their crush wore three weeks ago.

This isn’t proof they aren’t trying.
It’s proof that memory is built on meaning, not just effort. 

⚡ ADHD and the Attention Filter

For kids with ADHD, this internal “what’s important?” filter works a little differently.
The brain may struggle to regulate focus or decide which information matters most in the moment (Barkley, 2015).

This means:

• Important info can get lost in the shuffle.
  

• Boring or repetitive tasks may not even register as “worth storing.”
  

• Emotional or novel information still gets through—but often not what the teacher intended.
  

So when a student with ADHD forgets a key concept from class, it’s not because they didn’t care or didn’t try.
Their brain just didn’t tag that info as meaningful—because it didn’t feel meaningful at the time.

💥 Why “Trying Harder” Can Backfire

Here’s where the myth really falls apart.

“If they just tried harder, they’d remember it.”

Trying harder—especially when under pressure or anxiety—can actually hurt memory.

A recent neuroscience study found that stress-related signals can block the brain’s ability to encode and consolidate long-term memories, especially when the information is already hard to process (Fries et al., 2021).

In other words, the more a student forces themselves to remember, the more likely they are to blank out.

It’s not about trying harder.
It’s about making the brain feel calm, curious, and connected.

🔗 Strategies That Actually Help Math Stick

Here’s the good news: You can teach math in a way that works with the brain—not against it.
Here are a few strategies I use in tutoring neurodivergent students:

1. Tie Math to Real-Life Security

Link math to things that represent safety: money, jobs, housing, food.
Example: Show how budgeting skills could help them save for something important to them.

2. Tap into Social Relevance

Make it about relationships or friendships.
Example: Use scenarios like splitting costs at a birthday party or figuring out time zones to call a long-distance friend.

3. Use Humor, Stories, or Emotions

Wrap concepts in stories, jokes, or emotional moments.
Brains love stories. They remember feelings better than formulas.

4. Avoid Pressure, Create Curiosity

Instead of drilling and testing, use questions that spark wonder.
Less “What’s 6 × 8?” and more “How many cookies would we need if everyone in your friend group wanted 6?”

💡 SIDEBAR: Focused vs. Diffuse Thinking (from A Mind for Numbers)

In her book A Mind for Numbers, Barbara Oakley explains that learning happens best when we switch between two modes of thinking:

• Focused Mode: This is detail-oriented thinking—used when actively solving problems.
  

• Diffuse Mode: This is big-picture thinking—used during breaks, daydreaming, or when we reflect. It helps the brain make deeper connections.
  

Students with ADHD often struggle to stay in focused mode—or overuse it and burn out.
Encouraging them to take breaks, use real-world metaphors, or visualize math concepts helps activate diffuse mode and improves memory.

Both modes matter—but it's the balance that really helps things stick.

P.S. if you’re into the science of learning, A Mind for Numbers is a must read!

✨ Final Tips

The next time your child forgets a math concept they just learned, pause before assuming they didn’t try.
They may have been trying so hard, their brain locked up under pressure.  

When we understand why do students forget what they have learned, we can finally let go of the myth that it’s all about effort.
It’s about making learning feel safe, connected, and meaningful.

Because when math finally feels relevant, the brain pays attention.

📚 Works Cited

• Barkley, R. A. (2015). Taking Charge of ADHD: The Complete, Authoritative Guide for Parents. Guilford Press.

• Fries, G. R., Scaini, G., & Walss-Bass, C. (2021). The stress-induced shift from goal-directed to habitual behavior is associated with alterations in memory systems: Implications for ADHD and stress disorders. Neurobiology of Stress, 15, 100366. https://www.sciencedirect.com/science/article/pii/S2213158221001066

• LeDoux, J. (2012). Rethinking the emotional brain. Neuron, 73(4), 653–676.

• Oakley, B. (2014). A Mind for Numbers: How to Excel at Math and Science (Even If You Flunked Algebra). TarcherPerigee.