Science Exam Mistakes High Achievers Make

A student who usually scored above 85 percent on science exams got a big shock during his preliminary exams. He ended up with just over 50 marks — not because he didn't know the material, but because he missed shading one answer on the answer sheet. This small mistake caused all his following answers to shift by one row, costing him many marks. His story is a reminder that doing well on science exams takes more than just knowing the content.

The student's tutor, Jayce Or, is the founder of Germinate Learning, a science enrichment school for primary students. Or says the boy was confident about the questions but was careless with a simple but important step — shading his answer sheet correctly. 'His content knowledge was never the problem,' Or explains. 'Overconfidence led him to focus only on the big task of solving the questions.' After that experience, the student paid close attention to every step, no matter how small, and did well in his PSLE.

Or has more than 20 years of experience teaching science in primary schools and tuition centres. He says one of the biggest misconceptions about the PSLE Science exam is that careless mistakes only happen to weaker students. In reality, he says, stronger students make these mistakes too. To do better, students need to build careful observation skills, scientific precision, and good answering habits.

One common mistake is misreading data in tables or graphs. Students often mix up increasing and decreasing trends, or they jump to conclusions without studying the data carefully. For example, if one container cools down more slowly than another, some students wrongly think it is a better conductor of heat — but it is actually the poorer conductor that loses heat more slowly. Or advises students to circle trends, highlight key values, and compare results step by step before writing any answer.

Another mistake is confusing cause and effect. Students sometimes mix up which event caused which. For example, 'The plant wilted because it did not get enough water' might be wrongly flipped to 'The plant did not get enough water because it wilted.' Students should ask themselves what caused the change and what was the result, keeping the order of events clear.

Ryan Woo, deputy director of enrichment at The Eton Academy by EtonHouse, points out that students often give answers that only partially address the question. If asked why water in beaker A evaporated faster than beaker B, a weak answer would be: 'Water gains heat and evaporates.' A stronger answer would explain that beaker A had a larger exposed surface area, which allowed more water to contact the surrounding air. Woo advises students to look for comparison words like 'faster than,' 'more than,' or 'lower than.'

Woo also warns about misreading key instruction words. There is a big difference between 'decrease by' and 'decrease to' — one means you subtract from the original, while the other gives you the final value directly. He tells students to circle words like 'by,' 'to,' 'from,' and 'after' in data questions. Or adds that students should also underline phrases like 'based on the diagram' so they stay focused on the context given.

Using the wrong language is another common problem. Students sometimes say 'the ice disappeared' instead of 'the ice melted into water,' which is not scientifically precise. Students should also avoid inferring more than the data shows — for example, saying 'fertiliser improves health' when the data only shows the plant grew taller. Sticking to what the data actually says is the safer and smarter approach.

Lim Siew Hui, a senior teacher at Qihua Primary, says poor time management is another trap. When students rush, they skip steps or check their work too quickly, missing the important middle step of processing the question carefully. She advises students to know when to move on from a hard question, mark it, and come back to it later. Being aware of how many marks a question is worth can also help students decide how much time to spend on it.

Teachers say there are good strategies to help students reduce mistakes. Woo teaches his students to pause before answering and identify the command word, the key condition, and any trap word. Or suggests setting aside time at the end of the exam for purposeful checking of keywords and graph interpretation. Ee teaches the ACE mnemonic — Annotate important information, list Concepts, and Explain using scientific concepts — to help students process questions more carefully.