MathsIndex is a curated catalogue of interactive tools and resources for secondary maths teachers. Every tool on the site has been selected for one reason: it helps pupils build conceptual understanding, not just procedural fluency.
There is no shortage of maths resources online. The problem isn't finding something, it's finding something good. Many resource sites aim for breadth, listing hundreds of links with a sentence of description and leaving teachers to sift through and evaluate each one. MathsIndex takes the opposite approach. The catalogue is deliberately small. Each tool is here because it does something genuinely useful in the classroom, and each comes with a detailed teacher-facing guide explaining what the tool does, how to use it, and, most importantly, why it works.
Fluency matters. Pupils need to be able to factorise, calculate a mean, and apply circle theorems efficiently and accurately. But fluency built only on memorised procedures is fragile. It breaks down the moment a question is phrased differently or a problem doesn't match the practised template.
The tools on MathsIndex are chosen because they help pupils develop fluency with the concepts themselves, so that their fluency is flexible. That means tools where pupils can vary one thing and see what changes, test a conjecture and get immediate feedback, or explore the boundaries of a mathematical idea rather than just repeating its steps. A tool that lets pupils see why the area of a shape can grow while its perimeter stays the same is doing different work from a tool that simply checks whether they calculated both correctly.
The site is organised around the major strands of the secondary curriculum: Number, Algebra, Geometry, Ratio and Proportion, and Statistics. Tools come from a range of sources, some are built by the author on the sister site sensemake.uk, others are established third-party resources from platforms like GeoGebra and MathsBot. What they share is a focus on making mathematical structure visible and interactive.
Every tool page includes a written guide covering how the tool works, suggested classroom uses, and discussion questions designed to draw out the key mathematical ideas.
MathsIndex is a growing catalogue. If you know of an interactive tool that belongs here, something that helps pupils think mathematically, not just answer correctly, you can suggest it using the link in the sidebar.