The '-er/-est' Rule: The Linguistic Secret to Better Marks

A Secondary 2 pupil writes a full paragraph explaining why one metal conducts heat faster than another. The science is correct, the reasoning is sound, and yet the marker still deducts a mark. The reason often has nothing to do with the science at all. It comes down to a single missing letter.

This is the quiet trap behind comparative answers in science. Pupils who understand concepts perfectly well can still lose marks because their sentences are not actually comparing anything, at least not in the way examiners are trained to look for. The fix is refreshingly simple once you know what to look for, and it starts with two small suffixes: "-er" and "-est."

Why Comparative Words Carry So Much Weight

Science exams often ask pupils to compare two or more things, such as which material insulates better, which surface has more friction, or which solution is more acidic. These questions are testing whether pupils understand a relationship, and that relationship needs to be expressed using proper comparative language.

Writing "the metal is hot" tells the marker very little. Writing "the metal is hotter than the plastic" tells the marker exactly what is being compared, and how. That single "-er" turns a vague observation into a precise, markable comparison. This is why examiners are trained to look for comparative words rather than general descriptions, since the comparative form shows understanding of the relationship between variables.

The Basic Rule, Explained Simply

The rule itself is one most pupils already know from English lessons, they simply forget to apply it in science. It is one of the small habits that any good secondary science tuition programme will drill early, since it applies across biology, chemistry, and physics answers alike.

• Use "-er" when comparing exactly two things: hotter, faster, denser, stronger

• Use "-est" when comparing three or more things, or picking out the extreme case: hottest, fastest, densest, strongest

• For longer words, use "more" or "most" instead of adding the suffix: more soluble, most reactive

Here is how this plays out in a typical exam answer:

Weak Answer	Improved Answer
Copper conducts heat well.	Copper conducts heat faster than plastic.
Metal A is a good conductor.	Metal A is a better conductor than Metal B.
The acid reacted quickly.	Solution X reacted more quickly than Solution Y.

Notice that the improved answers all name what is being compared, rather than simply describing one item on its own. That naming is often the exact difference between a full mark and a partial one. Building this habit early pays off later, and this is exactly where Sec 1 is the critical year to kickstart science tuition, since comparative answering becomes more demanding as topics grow more technical in the upper secondary years.

Where Pupils Commonly Slip Up

Many secondary pupils understand the science content but lose marks in three recurring situations. The first is describing only one object without a point of comparison, such as "the ball rolled fast" instead of "the smoother ball rolled faster than the rough one." The second is switching to descriptive words instead of comparative ones under exam pressure, especially when pupils are rushing to finish a paper. The third is forgetting the suffix entirely and writing "more hot" instead of "hotter," which examiners may still accept depending on the syllabus, but which reads less precisely.

These slip-ups are rarely about a lack of scientific knowledge. A pupil can understand exactly why one material insulates better than another, yet still lose marks simply because the sentence on the page does not show that understanding clearly enough. Recognising this gap between knowing and writing is often the first step towards fixing it. Pupils who develop the habit of comparing correctly from early on tend to carry it through to more complex chemistry and physics questions later, where precise comparative language becomes even more important for scoring well.

A Quick Habit That Makes a Difference

One simple habit pupils can build is to pause before writing any descriptive sentence in a science answer and ask themselves whether the question is asking for a comparison. If it is, the sentence should name both items being compared and use the correct "-er" or "-est" form, or the equivalent "more" or "most" construction for longer words.

This small checking habit takes very little time to apply, but it consistently closes the gap between answers that sound scientifically correct and answers that earn full marks. It is often one of the first and most effective skills a good tutor will drill, precisely because it applies across biology, chemistry, and physics questions alike.

Group revision can help too, since pupils tend to notice each other's missing comparative words more easily than they notice their own, especially when reading answers aloud during practice sessions. Reading a classmate's answer with fresh eyes often reveals gaps that are easy to miss in your own writing, simply because you already know what you meant to say.

Conclusion

The "-er" and "-est" rule is a small linguistic detail with a surprisingly large impact on science exam marks. Once pupils get into the habit of naming what they are comparing and using the correct comparative form, their answers become sharper and easier for examiners to mark favourably, without needing to change anything about their scientific understanding.

If your child needs more structured support turning strong science knowledge into strong exam answers, Heuristics Science offers science tuition for both primary and secondary pupils in Singapore, built around our specialised TCR Answering Technique. Paired with guided practice and hands-on practical applications, our approach helps pupils express what they know clearly and confidently in every exam. Reach out to Heuristics Science today to find out how we can support your child's science learning journey.