Learning
Edition 09 | September 2025
From Learning Data to Classroom Instruction
Explore how data-driven insights can transform teaching by addressing
misconceptions and fostering deeper understanding.
Correct answer: Option B
Most Common wrong answer: Option D
What is the Question Testing?
This question tests whether learners truly understand the law of reflection: the angle of incidence
equals the angle of reflection. The twist is that the reflecting surface shown is rough. Students are
expected to recognise that roughness does not cancel the law—it still holds at every point of the
surface. What changes is that different points reflect rays in different directions, producing diffused
reflection instead of a single, clear reflected ray.
What is the Most Common Wrong Answer and Possible Misconception?
- Most Common Wrong Answer: Option D
- Percentage of Students Choosing Option A: 41.5%
Distractor Explanation :
- Option D (Cannot say as it is a rough surface):The largest group assumed that the law of reflection simply “fails” on rough surfaces. They confused the scattering of rays with the law itself being invalid.
- Option A (30°):A sizeable group subtracted the incident angle from 90° , mistakenly treating the reflection angle as complementary instead of equal
- Option C (90°):Some imagined the ray bouncing back perpendicularly, showing a lack of grounding in the rule itself.
Consequences of Children Not Developing This Concept
- Conceptual Confusion in Physics: Students may carry the belief that physical laws stop working under certain conditions. This undermines their confidence in the reliability of science
- Long-Term Learning Gaps: Misunderstanding reflection can create difficulties in optics topics such as mirrors, scattering of light, vision, lenses, and even wave behaviour in higher classes.
- Loss of Trust in Science Principles:Students risk seeing science as inconsistent, which can erode both curiosity and persistence in problem-solving.
How Should I Remediate This in My Class?
Concrete Demonstrations:
- Shine a torch on a smooth mirror versus a rough wall. Show that on the mirror, rays reflect in one direction, while on the wall, they scatter. Then emphasise: at each point, the law still holds.
- Use a cricket ball analogy: on a flat pitch, the ball bounces predictably; on uneven ground, it scatters—but each bounce still obeys the laws of motion.
- Keep repeating the idea: Angle of incidence = Angle of reflection, always.
- Contrast regular reflection with diffused reflection using side-by-side diagrams, highlighting that surface irregularity changes directions, not the law.
- Pose the question: Does roughness cancel the law, or just change the direction of rays?
- Encourage students to explain in their own words why scattering happens, but the principle remains intact.
Teacher Takeaway:
When students say, “It’s rough, so the law doesn’t work, ” they reveal a powerful misconception. Use hands-on demonstrations and analogies to show them that laws in physics are universal—what changes is how they play out in different conditions. Helping them see this will strengthen both their conceptual clarity and their trust in science as a disciplineEnjoyed the read? Spread the word
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