Learning with MatrixMind
What this site teaches, who it is for, and how the pieces fit together.
What this is
MatrixMind is a free educational site with two halves that support each other. The first is practice: abstract reasoning puzzles of the kind used in school entrance tests, cognitive assessments and job screening — matrix grids, sequences, rotations, odd-one-out. The second is explanation: 39 written guides to the mathematics, science and reasoning those puzzles are built from.
Practice without explanation produces people who are good at one test format. Explanation without practice produces people who understand an idea and cannot apply it under time pressure. The point of putting both here is that neither half works well alone.
Everything runs in a browser. Nothing needs an account, an install or a payment.
Who it is for
- Students aged roughly 11–16 preparing for entrance exams, CAT tests or non-verbal reasoning papers.
- Anyone revising school maths or science who wants the reasoning behind a rule rather than the rule alone.
- Home-educated students working independently, who need material that explains itself without a teacher in the room.
- Teachers and parents looking for something to point a student at that is neither a worksheet nor a video.
The writing assumes no prior knowledge beyond ordinary school arithmetic, and it does not talk down. Where something is genuinely hard — conditional probability, why an orbit is free fall — it says so and then explains it properly.
What is covered
Mathematics — 15 articles
- Counting things without listing them
- Probability, and why your intuition about it is wrong
- Prime numbers: the atoms of arithmetic
- Fibonacci, the golden ratio, and how things grow
- Clock arithmetic: what happens when numbers wrap around
- Pascal's triangle, and the patterns hidden in it
- Binary, and why ten was never special
- What a proof is, and why checking a million cases is not one
- Estimation: getting the right answer to within a factor of ten
- Angles, polygons, and why the rules are not arbitrary
- Sets, Venn diagrams and the words that trip people up
- Graphs and networks: the maths of things that are connected
- Averages, and the three ways they mislead you
- Ratio, proportion, and why doubling the size is not doubling the material
- Why there are letters in mathematics
Science — 9 articles
- How science actually decides what is true
- Measurement, units, and the errors that destroy spacecraft
- Forces and motion: three laws that took two thousand years
- Energy, and why perpetual motion is impossible
- Waves: one set of rules for sound, light and everything else
- Atoms, elements, and why the periodic table is shaped like that
- Electricity: what is actually moving, and what is not
- Gravity and orbits: falling, and missing the ground
- Evolution by natural selection: three conditions and a consequence
Reasoning — 15 articles
- How matrix reasoning puzzles actually work
- Rotation, reflection, and how to tell them apart
- Reading a sequence: how progressions are built
- Odd one out: reasoning by exclusion
- When more than one rule is running at once
- The traps that catch good solvers
- Getting faster without starting to guess
- Analogies: A is to B as C is to what
- Symmetry, and the four kinds worth knowing
- Why these puzzles feel hard, and what to do about it
- Number patterns hiding inside picture puzzles
- Nets, folding and three-dimensional rotation
- How to practise so that it actually sticks
- Deduction and induction: the two moves behind every puzzle
- What these tests actually measure, and what they do not
How it maps to school topics
Most of this material overlaps directly with secondary curricula. The mapping is approximate — syllabuses differ — but it shows where each article fits.
How to use it
- Read the article for whatever you are stuck on. They are written to be read once, carefully, rather than skimmed.
- Say the rule in a sentence before you look at any answer. This one habit does more for reasoning scores than any amount of extra practice.
- Practise in short sessions. Twenty minutes a day beats four hours on a Sunday, by a wide margin and for well-understood reasons.
- Keep an error log. Write down what went wrong, not just that it did. Most people have two or three recurring failure modes, and naming them is most of the fix.
There is a fuller version of this in How to practise so that it actually sticks.
What this is not
It is not a qualification, and it is not a replacement for a teacher. It is also not a claim that reasoning tests measure intelligence or worth — they measure a narrow, trainable, timed skill, and one of the articles here is devoted to being honest about their limits.
If a test stands between you and something you want, practising for it is worth doing. The underlying skills — separating variables, checking one thing at a time, describing a relationship precisely, noticing what stays constant — are worth more than the score, and they transfer well beyond any exam.