About Izzi Math
Free maths practice for families, kindergarten through fifth grade.
What this is
Interactive maths books and games for K–5, where every activity also exists as a printable sheet with an answer key. It is built for parents at home rather than for schools. There are no accounts, no ads, and nothing to buy.
How it works
Problems come from seeded generators, and the seed lives in the page’s web address. That means two useful things. A sheet is reproducible — the same link always gives the same problems, so you can print a page today and do it on screen tomorrow. And the practice never runs out, because a new seed gives a fresh set of problems from the same generator.
There is no login because there is nothing to store. The address bar is the save file.
Books, games, and sheets
| Books | Guided practice with hints and worked explanations. Never timed — thinking time is the point. |
| Games | Short replayable rounds for building speed. Timers are off by default and always one click to disable. Nothing is scored against anyone else. |
| Practice sheets | Problems grouped by type, with clear instructions. Use these while a skill is new. |
| Review sheets | Eight problems, shuffled so no two next to each other need the same method. Use these a week or two later. |
Where the content comes from
The order topics appear in follows the Illustrative Mathematics K–5 sequence, which is free, openly licensed and coherent across the whole grade band.
Which activities got built is a separate question, and that followed the research rather than the curriculum. The strongest evidence in primary maths is attached to particular practices rather than to any brand of curriculum — so the site leans on the ones that have held up: linear number lines, fraction number lines, brief-exposure subitizing, part-whole number bonds, area models, and mixed review.
Two examples of that showing up in the build. The Great Race is a straight implementation of a game from Siegler and Ramani’s work, including the detail that the child names the squares they pass through, counting on from where they are — that detail roughly doubled the effect in a later study, so tapping “one, two” is treated as an error and corrected. And review sheets hold eight mixed problems — five in Kindergarten and grade 1, where eight will not fit on one page at that type size — because a randomised trial of 787 students found the same problems shuffled that way scored 61% against 38% a month later.
Being honest about the evidence
Illustrative Mathematics is rated highly for design quality — EdReports places it at “meets expectations” in all three gateways at every grade K–5. That is not the same as proof that it raises attainment, and there are no high-quality studies of IM K–5 learning outcomes. The impressive effect sizes usually quoted for IM come from grades 6–8, not from primary. We use it as a well-vetted plan, not as a guarantee.
Every citation, what it found, how it is used, and which activities rest on it is on the references page — including the sources that shape what we deliberately do not build.
Which parts are evidence, and which are taste
Worth separating, because almost nobody in this category does. The mechanics are evidence-led: the number lines, the board game and its counting rule, the interleaved review sheets, the strategy shown before any timer, the decision not to build dot-comparison training. Each of those traces to a specific finding, named on the references page.
The rest is craft judgement, and we are not going to dress it up: the characters, the colours, the aesthetic, the paper-and-screen pairing, and the idea of putting the seed in the address bar. Those are design bets. They may well be good ones. They are not findings, and you should not weigh them as if they were.
Assessment
Izzi Math is practice, not assessment. It never produces a score and never predicts one. If your child has taken the Rapid Online Assessment of Maths, the score page can point you at matching practice — but you do not need a score, or any assessment, to use anything here.
Credits
Built by the Brain Development & Education Lab at Stanford. Curriculum sequence from Illustrative Mathematics. Activity designs drawn from the maths education research literature, credited in full in the repository.