A full experiment answer has three parts: a claim, the evidence that supports it, and the scientific reason that links them. Writing all three in two or three short sentences is what moves an answer from half marks to full marks.
This page belongs to the SPM Science learning guide. It is for the student who reads the data well but loses marks on the written conclusion.
What does the problem sound like?
“I knew the answer. I wrote that the temperature went up. The teacher wrote ‘explain’ in the margin and gave me one mark out of three.”
The idea was correct, but the answer stopped at an observation. Three marks usually reward an observation, a comparison and a reason.
What is the pattern?
Use three short parts, each one sentence.
- Claim: the conclusion, answering the question in plain words.
- Evidence: two values from the data, with units, and the difference between them.
- Reason: the scientific idea that explains why the evidence leads to the claim.
The pattern works because it forces the answer to name what the data shows before it explains. The claim evidence revision desk lets you practise rewriting an answer into these three parts.
Worked example: seed germination
An original experiment tested how water affects germination. Twenty seeds were placed in each of three dishes and left for five days. Each dish was kept at 28°C in the same light.
| Dish | Water added each day | Seeds germinated out of 20 |
|---|---|---|
| A | 0 mL | 0 |
| B | 5 mL | 16 |
| C | 25 mL | 6 |
Question (3 marks): What conclusion can be drawn about the amount of water and germination?
A weak answer: “Dish B had the most seeds growing. Water is needed for germination.”
This states one true fact and one general idea, but it does not compare and it ignores Dish C.
A strong answer:
- Claim: A moderate amount of water gave the highest germination, and too much water reduced it.
- Evidence: Dish B, with 5 mL a day, germinated 16 of 20 seeds, while Dish A with no water germinated none and Dish C with 25 mL germinated 6.
- Reason: Seeds need water to start growing, but too much water can leave too little air around the seed for respiration.
The reason gives a scientific idea for each direction of the trend, which is what the third mark tests.
Which wording slips lose marks?
| Slip | Example | Repair |
|---|---|---|
| Direction without amount | “It went up” | “It rose from 30°C to 50°C” |
| Data without meaning | “16 seeds germinated” | Add what the number shows compared with another dish |
| Claim too strong | “Water always helps” | “Within these three amounts, 5 mL gave the best result” |
| Reason missing | “Because it is better” | Name the process, such as respiration or evaporation |
Also check that all other conditions were kept the same. Here light and temperature were equal, so the conclusion is about water only.
What if the data does not settle the question?
Here only three amounts of water were tested. The data cannot say that 5 mL is the best possible amount, because 8 mL was never tried. A careful sentence adds: “A further test between 5 mL and 25 mL would show the best amount.”
This is the same habit you practise in evaluating a science claim from a supplied dataset.
What can you do this week?
- Pick three experiment questions from your textbook or past school tests.
- Write each answer as three labelled lines: claim, evidence, reason.
- Underline the numbers in your evidence line. If there are none, add two.
- Read your reason line and ask, “Does this name a process or idea?”
- Log your slips in the mistake log and paper-error review.
When might one-to-one tuition be worth considering?
Consider it when you can follow a model answer but cannot produce one yourself, or when the same comment, such as “explain” or “be specific”, returns on your corrected papers. A teacher can work on your own sentences, which a textbook cannot do.
See online one-to-one Science tuition. The one-hour trial class (from RM50) is a real taught lesson, so you can bring a marked answer and see how the teacher works with it.