You prepared the lesson carefully. You explained the topic, shared examples, answered questions, and gave students time to practice. Three weeks later, you hand out an assessment — and the results feel like a reset button. Most students barely remember what you covered. Some look at the questions as if they had never heard of the topic before. Understanding why students forget what they learn is one of the most important questions a teacher can ask — and the answer has everything to do with how learning experiences are designed.
If this sounds familiar, you are not alone. Research on the forgetting curve shows that without reinforcement, students can forget up to 70% of newly learned material within just 24 hours. A 2017 analysis published by Edutopia, drawing on neuroscience research by Richards and Frankland, confirmed that forgetting is not a failure of memory — it is an evolutionary strategy where the brain discards information that is not actively reinforced. The pattern is not a reflection of your teaching quality or your students’ effort. It is a natural feature of how memory works.
The frustration is real. So is the quiet guilt — “Maybe I didn’t teach it well enough.” But before blaming yourself or your students, consider this: the issue may not be effort at all. It may be the type of learning experience you are designing.
Why Students Forget What They Learn: Surface-Level Learning Is the Real Problem
Education researchers distinguish between two types of learning. Understanding deep learning vs surface learning is essential for any teacher who wants lasting results. Surface learning happens when students memorize facts, definitions, or procedures to pass a test — without connecting them to broader meaning. Deep learning happens when students relate ideas, analyze them critically, and apply knowledge in new contexts. This distinction is fundamental to developing 21st-century skills that go beyond memorization.
The difference matters. According to research by Ventura et al. (2024), approximately 90% of classroom instruction stays at the surface level, limiting students’ ability to engage in deep or transfer learning. This means most classroom experiences — lectures, note-copying, repetition-based tests — unintentionally train students to forget.
Surface learning is not a failure of intelligence. It is a predictable result of instructional design. When the primary goal is content delivery and the primary assessment is recall, the brain encodes information in a way that fades quickly. Students learn “for the exam,” and once the exam passes, the content has no further use — so the brain lets it go.
What Surface Learning Looks Like in Practice
- Students can repeat a definition but cannot explain the concept in their own words.
- Students pass a test on Friday but cannot apply the same knowledge to a new problem on Monday.
- Students copy notes accurately but do not know how to use those notes to solve real questions.
These are not signs of laziness. They are signs that the learning experience stayed shallow — and that is something you, as a teacher, have the power to change.
Why the Brain Remembers What It Uses and Connects
Neuroscience and learning research offer a clear insight: the brain retains information that it uses, explains, applies, and connects to real situations. As Edutopia reports, memories are not stored like files in a cabinet. They are more like spider webs — strands of recollection distributed across millions of connected neurons. The more connections a piece of information has, the harder it is to forget.
This is why students who explain a concept to a peer remember it better than students who simply re-read their notes. Research by Sekeres et al. (2016), published in Nature Neuroscience, found that peer-to-peer explanations reactivate, strengthen, and consolidate fading memories. It is also why students who solve real-world problems retain knowledge retention rates far above those who memorize answers for a test.
Three Principles of Lasting Knowledge Retention
- Use it or lose it. The brain prioritizes information it uses repeatedly. If content is only encountered once — during a lecture — it fades. Retrieval practice — the act of actively recalling information rather than passively reviewing it — creates stronger neural pathways and is one of the most evidence-backed methods for improving memory. Activities that require students to retrieve and apply knowledge build exactly these pathways.
- Space it out. Spaced repetition — returning to content at increasing intervals over time — directly counters the forgetting curve. Instead of reviewing everything once before a test, students who revisit material in shorter, spread-out sessions retain far more over the long term. Even simple check-ins across multiple lessons make a significant difference.
- Connect it to what matters. Information anchored to real problems, personal experience, or emotional engagement survives longer. When students see why something matters — not just what it is — memory improves. Explaining ideas to others forces the brain to organize, clarify, and reinforce what it knows.
These principles point in a clear direction: active learning approaches — project-based learning, Design Thinking, and collaborative inquiry — create exactly the conditions the brain needs to move from surface learning to deep, lasting understanding. They are not a trend. They are aligned with how memory actually works.
How Active Learning Changes What Students Remember
Consider two classrooms studying the same topic: water conservation and its connection to SDG 6 (Clean Water and Sanitation).
Classroom A (Traditional approach): The teacher explains the water cycle, students copy notes, and two weeks later they take a test with fill-in-the-blank questions. Most students pass the test. A month later, few can explain why water conservation matters or how it connects to their community.
Classroom B (Design Thinking + project-based learning approach): A teacher in Buenos Aires presents a challenge to her 13-year-old students: “How can we reduce water waste in our school?” Following a Design Thinking process, students empathize with their school community, define the core problem, research local water usage, interview maintenance staff, and measure consumption at water fountains. They ideate solutions, prototype their best ideas, and present their findings to a partner classroom in Hyderabad, India — where water access is an entirely different challenge. Both groups debate solutions, compare contexts, and reflect on what they learned together.
In Classroom B, students are not just remembering facts — they are building knowledge through investigation, collaboration, and real-world application. A meta-analysis by Chen and Yang (2019), published in Educational Research Review, reviewed 46 comparative studies and concluded that students in project-based learning environments achieve better academic results than those in traditional instruction, with particularly strong effects in conceptual understanding and knowledge application.
Meanwhile, a 2025 systematic review published in Frontiers in Education confirmed that design thinking in education improves the learning experience by encouraging active participation, critical thinking, and interdisciplinary collaboration — and transforms pedagogical practices by promoting innovation in the design of student-centered educational activities.
What Changes in the Classroom
When active learning guides instruction, students:
- Ask questions instead of only answering them.
- Collaborate with peers — including peers from other cultures and countries — to explore different perspectives. This is the foundation of collaborative online international learning (COIL).
- Apply content to real problems rather than memorizing it in isolation.
- Follow a Design Thinking process — empathize, define, ideate, prototype, test — that structures their creative problem-solving.
- Reflect on what they learned and how they learned it, developing metacognitive skills that support long-term knowledge retention.
These are the conditions that move learning from “I memorized it for the test” to “I understand it and can use it.” You can see how this works in practice in the article How Project-Based Learning and Global Collaboration Work Together.
Student Retention Strategies You Can Apply This Week
Now that you understand why students forget what they learn, you do not need to overhaul your entire curriculum to start shifting from surface to deep learning. These student retention strategies can be introduced one at a time, starting with your very next lesson.
Choose a topic from your upcoming plan. Instead of explaining it directly, frame it as a question your students can investigate: “How does [this topic] show up in our community?” Let them research, discuss in groups, and present what they find — even in 30 minutes. That cycle — question, investigation, production, presentation — is the core of project-based learning.
Build in retrieval practice at the start of each class: ask students to recall — without notes — two or three key ideas from the previous session. Combine this with spaced repetition by revisiting those same ideas again one week later and once more before the unit ends. This rhythm, more than any single lesson, is what moves knowledge from short-term to long-term memory.
If you add a Design Thinking lens — asking students to empathize with real people affected by the problem before proposing solutions — you deepen the experience even further. Design Thinking gives students a structured way to connect academic content to human reality, which is precisely what the brain needs to hold onto what it learns.
This Already Exists on the Platform
In Class2Class, every project is already designed around an authentic challenge that students investigate, discuss, and respond to with a real product. When you open a project on the platform, you will see activities structured around project-based learning and Design Thinking phases — so that students use, connect, and apply what they learn. The Global Collaboration Essentials in the Learning Space walks you through everything: from understanding the foundations to designing and leading your first global project.
You Can Move from “They Don’t Remember” to “They Use What They Learn”
If you have asked yourself why students forget what they learn, the answer is not to teach harder or test more often. The answer is to design learning experiences where students actively use, connect, and apply knowledge — experiences that respect how the brain actually works.
This is not about blaming students or blaming yourself. It is about recognizing a truth that research has made clear: the type of experience matters more than the amount of content. Every instructional decision you make — how you frame a question, how you organize group work, how you connect content to the real world — either moves students closer to deep learning or keeps them on the surface.
You already have the expertise and the intention. The next step is yours.
References
- Chen, C. H., & Yang, Y. C. (2019). Revisiting the effects of project-based learning on students’ academic achievement: A meta-analysis. Educational Research Review, 26, 71–81. Read the study
- Frontiers in Education (2025). Design thinking as an active teaching methodology in higher education: A systematic review. Read the review
- Richards, B., & Frankland, P. (2017). The persistence and transience of memory. Neuron, 94(6), 1071–1084. As cited in Edutopia
- Sekeres, M. J. et al. (2016). Recovering and preventing loss of detailed memory. Nature Neuroscience. Read the paper
- Ventura, S. et al. (2024). Surface, Deep, and Transfer Learning in K-12 Instruction. Read the article