Aren't Bohr atoms a bit out of date?

For Year 7 to 9, no. The Bohr shell picture is wrong in detail at university level, but it's the right level of abstraction for KS3. It gives a student a usable mental model for valency, group properties, and ion formation. The more accurate orbitals picture would just confuse a Year 8. Curie will mention the model is a simplification when relevant, but won't pretend it isn't useful.

What's wrong with just memorising the rules for balancing equations?

It works for the specific equations memorised. It breaks the first time a new one appears. The point of the picture-first method is that the student isn't applying rules — they're noticing that the atom count must match. Once that intuition is in place, balancing any equation, including ones never seen, becomes a counting exercise.

Does Prof Curie give written worked examples?

Yes, in moderation. The order is usually: probe the model, draw the particle picture together, then a worked example with the symbolic notation, then a faded one (some steps removed), then independent. The worked example never comes first — it's the third or fourth move, not the opening.

How long until my child sees real benefit from this approach?

Realistically, three to four sessions for a topic the student has met before. Then, on the next new topic, the speed-up is visible. They'll spot conservation issues themselves, ask better questions, and the maths will feel less like a separate subject. The investment is real but front-loaded.

Models-First Chemistry: How Prof Curie Teaches the Picture Before the Numbers

In every KS3 chemistry topic, there's a version of the lesson that goes faster on paper and slower in the head, and another version that goes slower on paper and faster in the head. Prof Curie always picks the second one. Here's what that looks like in practice.

The three models that do most of the work

Curie's KS3 toolkit isn't large. Most of the heavy lifting is done by three model types, repeated across topics.

1. The Bohr atom

The classic concentric-shells picture of a nucleus with electrons orbiting in rings. Out of date for university chemistry, exactly right for Year 7 to 9.

It's used to explain why Group 1 metals behave the way they do (one electron in the outer shell, easily lost). Why noble gases don't react (full outer shell). Why ions form (gain or lose to get a full shell). Why the periodic table is arranged the way it is.

A student who can sketch a sodium atom and a chlorine atom on the back of a notebook can derive, with prompts, why NaCl is the formula. They don't memorise it. They build it.

2. The particle-in-a-box diagram

Little circles in a box. Closer together for solid, looser for liquid, scattered for gas. Used for everything around states of matter, dissolving, diffusion, gas pressure, the differences between mixtures and compounds.

This is the model where the most common KS3 misconceptions live. The "particles expand when heated" misconception is, at root, an inability to picture the diagram correctly. So Curie spends time on it — drawing, redrawing, asking the student to predict what the picture looks like before and after.

The dissolving lesson is the canonical example. Students often think the sugar disappears. With a particle picture, the sugar particles obviously still exist; they're just spread between the water particles. Same number of particles before and after. Conservation of mass becomes self-evident, not a rule to memorise.

3. The equation skeleton

Before coefficients, balanced equations are drawn as pictures. A reaction like:

methane + oxygen → carbon dioxide + water

…starts as a picture. One CH₄ molecule on the left. Two O₂ molecules on the left (after balancing). One CO₂ and two H₂O on the right. Count the atoms. They match.

Then — and only then — does the student write CH₄ + 2O₂ → CO₂ + 2H₂O. The numerals in front aren't arbitrary; they're how many of each picture you need to draw.

This sounds laborious. For the first three or four equations, it is. From the fifth onwards, it gets quick. By the tenth, the student is doing it in their head — but the picture is still what's running underneath.

A worked example: burning magnesium

This is a topic that appears in nearly every KS3 chemistry syllabus and is the canonical place for the conservation-of-mass misconception. A student burns magnesium in air, weighs the ash, and notes the mass has increased. They expected it to decrease (it's burned — surely it's smaller?).

Curie's session would go roughly like this. (Imagine a Year 8 student is on the other side.)

Probe. "Before we look at this, what do you think happens to the mass when you burn magnesium? Will it go up, down, or stay the same?"
The student says it goes down. Curie notes the misconception silently, doesn't correct yet.
Macro draw. "Let's draw what we'd see — a magnesium strip, on fire, becoming white ash. Good."
Submicro probe. "Now at the particle level — what's in the air around the magnesium?" The student says oxygen. "Right. So before the reaction, we have magnesium atoms in the strip, and oxygen molecules floating around. Draw that."
The student draws Mg on one side, O₂ molecules on the other.
Reaction. "When the reaction happens, the magnesium combines with the oxygen. Draw what the product looks like — magnesium oxide." The student draws Mg and O joined.
The question. "Look at your picture. Before the reaction, all those atoms existed. After the reaction — same atoms, just rearranged. So what should happen to the total mass?"
The student pauses. "It... stays the same?"
"If we counted the oxygen that's now stuck to the magnesium, what about the mass of just the solid?"
The student gets it. "Oh — it goes up because the oxygen is now part of the solid."
Symbolic. Now, and only now, comes 2Mg + O₂ → 2MgO. The student writes it. Curie asks how they know the 2 goes in front of the Mg. The student counts atoms.

The whole thing is maybe twelve minutes. The conservation of mass concept, conservation of atoms, and balancing of a simple equation are all in place. The student didn't memorise anything.

When Curie deviates from this method

Two situations.

First, when a student already has a solid model. The probes catch this. If a student answers cleanly that the mass goes up because oxygen is now part of the solid, Curie doesn't make them draw it — they've drawn it already, mentally. She moves on to a harder problem.

Second, when a student is too tired to draw. On amber-energy sessions she may verbalise the model rather than ask the student to draw it. The model still leads. The mode of expressing it shifts.

What this is not

It's not "discovery learning". The student isn't expected to invent the periodic table. Curie has the answers and structures the questioning to land them. It's also not "no maths". The maths arrives — it just arrives third, not first.

And it's not slow forever. The first three or four sessions on a new topic feel deliberate. By session six the same student is doing twice as much per minute as a student who learned the procedural version, because the picture underneath stops needing to be reconstructed each time.

What to expect as a parent

The visible artefact of a models-first session is usually a piece of paper with circles on it. If your child has been chatting with Curie and you ask what they did, "drew the molecules" is the answer you want to hear. "Did some equations" without any reference to drawing is the answer that suggests the session slipped procedural.

The school's own teaching may be more procedural — most KS3 schemes of work are. Curie's job isn't to compete with that; it's to ensure the picture underneath the school's procedure is in place. The two reinforce each other.

The connection to GCSE

It's worth saying explicitly: this approach pays off in GCSE chemistry, not just KS3. The topics that bite hardest at GCSE — empirical formulae, mole calculations, percentage yield, electrolysis — all assume a solid particle model underneath. Students who arrived at Year 10 with that model in place find these topics manageable. Students who didn't, find them opaque.

KS3 is the cheapest place to build the model. Year 7 to 9 is a long runway. By the time the GCSE pressure arrives, the foundation is silent infrastructure — and the student can spend their attention on the new material rather than backfilling.

Jason runs aitutors.me. He has a Year 8 child and about fifteen years of building software adjacent to education. Updated 21 May 2026.