Why Many Students Understand Science but Still Lose Marks in Exams

Many parents notice a frustrating pattern. Their child can explain a science topic at home, follow lessons in class, and even answer questions verbally. Yet when the exam results arrive, the marks are lower than expected.

For parents in Hong Kong’s highly competitive school environment—especially those preparing for IGCSE or IB science—this can be confusing and worrying.

In reality, this situation is very common. Many capable students lose marks not because they lack understanding, but because they have not yet developed the skills needed to communicate their knowledge effectively in exam conditions.

The good news is that these issues are usually very fixable once parents and students understand what is happening.

Below are some of the most common reasons students lose marks in science exams, even when they understand the material.

1. Not Understanding How Marks Are Awarded

One of the biggest surprises for students is that science exams do not simply reward knowing the topic. They reward answering questions in the specific way examiners expect.

Many capable students lose marks because they are unfamiliar with how mark schemes work. Exams reward precise responses that match the examiner’s criteria rather than general explanations.

For example, a question worth three marks usually requires three distinct points. If a student writes one long explanation instead, they may only receive partial credit.

What parents can do

Encourage students to practise with past exam questions and mark schemes. This helps them see exactly how marks are awarded.

2. Missing Key Scientific Keywords

Science exams reward precise terminology. Students who use everyday language instead of scientific terms often lose marks, even if their understanding is correct.

For example, in biology a student might write:

“The plant grows faster because it gets more light.”

While this shows some understanding, examiners may expect words such as photosynthesis, chlorophyll, or rate of reaction depending on the question.

Without these key terms, students may only receive partial marks.

What parents can do

Encourage students to learn and practise key scientific vocabulary for each topic.

3. Misreading the Question

Another very common issue is simply not answering the exact question being asked.

Science exam questions often include command words such as:

• describe

• explain

• compare

• evaluate

Each of these requires a different type of answer. If a student writes a description when the question asks them to explain, they may lose marks even if the information is correct.

What parents can do

Encourage students to read each question carefully and identify the command word first before writing their answer.

4. Giving Answers That Are Too Short

Many students write answers that are technically correct but too brief to earn full marks.

For example, a question asking for an explanation might require:

• a scientific concept

• a cause-and-effect explanation

• a relevant example

If the student provides only a short statement, they may only earn one mark when three were available.

What parents can do

Teach students to match the length of their answer to the number of marks available.

A useful rule is:

• 1 mark = 1 key point

• 2 marks = 2 key points

• 3–4 marks = a developed explanation

5. Difficulty Applying Knowledge to New Situations

Science exams often test application, not just memory. Students may understand the concept during lessons but struggle when it appears in a slightly different context.

For example, a student may understand the theory behind electricity but struggle when asked to apply that knowledge to a new circuit diagram.

This ability to apply knowledge improves with practice using exam-style questions.

What parents can do

Encourage students to regularly practise past paper questions, not just review notes.

6. Losing Marks Through Small Exam Mistakes

Sometimes students lose easy marks because of small but avoidable mistakes.

Examples include:

• not showing working in calculations

• forgetting units in physics or chemistry answers

• making careless errors under time pressure

• not checking their work

Many students lose marks simply by not reading questions carefully or providing enough detail.

What parents can do

Encourage students to leave a few minutes at the end of the exam to review their answers carefully.

Helping Your Child Improve Science Exam Performance

When science marks drop, it does not necessarily mean a student lacks ability. More often, it means they need support in areas such as:

• exam technique

• scientific vocabulary

• structured explanations

• practising exam-style questions

Once students understand how science exams work, their performance often improves quickly.

Supporting Your Child’s Success in Science

Science can be one of the most rewarding subjects for students, but it requires both understanding and exam technique. With the right habits and practice, many students who initially struggle with exam performance are able to rebuild confidence and significantly improve their results.

Parents who support regular practice, encourage clear explanations, and help students review exam questions carefully can make a meaningful difference to their child’s progress.