KS3 science is one national curriculum programme built from three disciplines, biology, chemistry and physics, plus a thread called working scientifically: predicting, testing fairly, and judging evidence. The best help at home is not teaching the content but asking your child to explain it, and to predict what would change if one factor did.
Schools choose the order, the pace and the year-by-year split, so what your child meets in Year 7 may differ from a friend's at another school. The content below comes from the national curriculum for England, which sets the shape across Years 7 to 9.
What the three sciences cover
Biology starts small and builds outwards. Cells and what each part does; how cells make tissues, organs and systems; the skeleton and muscles; nutrition and digestion; breathing and gas exchange; reproduction in humans and plants. Then the larger ideas: photosynthesis and respiration, food webs and how organisms depend on each other, and inheritance, with DNA, variation and natural selection.
Chemistry is built on the particle model: solids, liquids and gases as arrangements of particles, and changes of state explained by what the particles do. From there come atoms, elements and compounds, mixtures and ways of separating them (filtration, evaporation, distillation, chromatography), chemical reactions as the rearrangement of atoms, acids and alkalis and the pH scale, the periodic table, the reactivity series, and the Earth and its atmosphere.
Physics covers energy (stores, transfers and everyday costs such as fuel bills), motion and forces (speed, distance-time graphs, balanced and unbalanced forces, pressure), waves (sound and light), electricity and magnetism (current, potential difference, resistance, magnetic fields), and space: gravity, the seasons and the Earth's tilt.
Working scientifically runs through all three. Children are expected to make predictions, plan enquiries that identify independent, dependent and control variables, record and graph results, and evaluate how reliable they are. It is taught through the content, not separately, which is why a question can look like biology and really be testing fair testing.
- BiologyCells to ecosystems, inheritance
- ChemistryParticles, reactions, periodic table
- PhysicsEnergy, forces, waves, electricity
- Working scientificallyPredict, test fairly, evaluate
Where children get stuck
Most KS3 science difficulty is not missing facts. It is a wrong mental picture that survives the lesson. These are common ones; none is unique to any school.
- Plants "eat" soil. The curriculum describes plants making carbohydrates by photosynthesis and taking water and minerals from the soil. Most of a plant's dry mass is built from carbon dioxide in the air, which surprises adults too.
- Particles themselves melt, expand or get hot. In the particle model, the particles stay the same; their movement and spacing change.
- Forces are "used up" or something keeps an object going. The curriculum frames forces as needed to start, stop or change motion, not to keep something moving.
- Energy is a thing that gets used up. In the curriculum's version, the total energy has the same value before and after a change; it is transferred, not destroyed.
- Correlation equals a fair test. Changing two variables at once and trusting the result is a working scientifically trap.
What to try when your child is stuck
You do not need the answer. You need one good question.
Example 1 (biology). "Why does a plant in a dark cupboard go pale?" The wrong turn is "it didn't get water". Coax: "What does a leaf need light for? What does it make?" Let them reach photosynthesis themselves.
Example 2 (chemistry). "Why does ice melt when it warms up?" The wrong turn is "the particles melt". Coax: "Draw six particles in the ice. Now draw them in the water. What changed: the particles or how they're arranged and moving?"
Example 3 (physics). "A ball rolls along a smooth floor and slows down. Why?" The wrong turn is "it runs out of force". Coax: "What is touching the ball? What is that contact doing to its motion?" If they say friction, ask which way it pushes.
The pattern in all three: make a prediction first, then check it, then explain the gap. Children who commit to a guess remember the correction far better than children who are simply told.
- 1PredictCommit to a guess first
- 2CheckSee what actually happens
- 3Explain the gapWhy was it different?
What to try tonight
- Ask your child to teach you one thing from today's science lesson in under a minute, using a drawing.
- Pick one everyday object (a kettle, a torch, a houseplant) and ask, "What science is happening here?"
- Ask for a prediction before any experiment or recipe: "What do you think will happen if we change this?"
- Have them sketch the diagram they most dread, from memory, and compare it with the textbook.
- Write down three key words from the week and ask for a one-sentence definition without looking.
For a fuller revision method, see how to revise KS3 science, and for where science sits in the wider stage, what is Key Stage 3.
Where an app can fit
Heddy is an app with a separate professor for each science, and each teaches differently. Professor Darwin zooms from organism to molecule for biology; Professor Curie builds the particle picture before any equation; Professor Newton asks for a prediction before showing what happens. None of them hands over a final answer, which suits the kind of help above. It is one option; the questions in this article work with or without it.
Updated 30 Sep 2026. Written by Duke Harewood.
Questions people ask
What is taught in KS3 science?
The national curriculum for England sets out biology, chemistry and physics content for Key Stage 3, plus a strand called working scientifically: predicting, planning fair tests, handling data and evaluating. Schools decide the order and the year-by-year split, so it varies by school.
Is KS3 science one subject or three?
The national curriculum treats it as one science programme with three disciplines. Some schools teach it as one subject with mixed topics; others timetable biology, chemistry and physics separately. Check your child's school.
What is the hardest part of KS3 science?
For many children it is the move from remembering facts to explaining with a model, for example the particle model, energy transfers or food webs. Explaining why something happens is what later GCSE questions reward.
How can I help if I never studied science?
Ask your child to explain one idea to you and to predict what would happen if a factor changed. You do not need the answer; you need to ask good questions and let them find it.