Key Points

In the secondary stage, science transitions from simple observation to deep exploration, focusing not only on what we know but also on how we know it through experiments, measurements, and building models.

Science uses models, which are simplified representations of complex systems, to focus on the most important aspects for a given question. This makes complex phenomena easier to understand and study.

Creating a scientific model involves making deliberate choices and assumptions, such as ignoring air resistance when studying gravity, to simplify the problem and find a useful answer.

Many words from everyday life, such as 'force', 'work', and 'cell', have specific, unambiguous meanings in science to ensure clear communication among scientists worldwide.

Science uses a shared language of symbols to represent quantities like mass ($m$), velocity ($v$), and force ($F$), each associated with a defined unit.

Mathematics is used in science to express relationships between quantities clearly. An equation is a compact statement about these relationships, not just a tool for calculation.

Using standard international (SI) units, like the kilogram ($\text{kg}$), is essential to avoid confusion and errors, ensuring that scientific results are comparable and trade is fair.

A scientific law describes a regular pattern observed in nature, while a theory is a broader explanation. Both are based on evidence and can be revised.

Scientific theories have limits and can be proven wrong by new evidence. This openness to being corrected by nature is a fundamental strength of the scientific process.

Scientific thinking involves questioning claims and demanding evidence. For example, one can scientifically disprove the myth that food becomes harmful during an eclipse.

Making rough estimates is a crucial scientific skill. It helps build intuition, detect errors, and check if an answer is reasonable, which can be more important than exact calculation.

We can estimate the volume of air breathed in a day. By estimating breaths per minute (15) and volume per breath (0.5 L), we get about $15 \times 0.5 \times 60 \times 24 \approx 10,800$ litres per day.

Real-world problems like climate change or understanding how a face mask works require knowledge from multiple branches of science, such as physics, chemistry, and biology, working together.

Science is not just a collection of facts but a human activity driven by curiosity, creativity, collaboration, and careful questioning. It develops through the work of many individuals over time.