How the words are chosen

Every word a Tadpole game asks a child to spell has a reason to be there, and the reason is recorded alongside the word.

What makes a word hard

A word’s level comes from what you have to know in order to spell it: the sounds and letter patterns it uses, and the prefixes, suffixes and roots it is built from. The hardest of those is what decides where the word sits. night needs the “igh” pattern. jumping needs jump plus the “-ing” ending, so it cannot arrive before either. possession needs possess plus “-ssion”, which is several years further on. Where a word can be built more than one way, the easier way wins.

When children actually meet the word

Spelling difficulty on its own is not enough. administration is no harder to sound out than night, so on letters alone it would land in the same infant year, and no six-year-old has that word. Every word is therefore also checked against published research into the age at which children learn words, a set of ratings covering just over 31,000 of them. That check can only hold a word back. It never brings one forward.

A published list beats a calculation

Where a curriculum publishes the actual words, those words go where the curriculum puts them. In England that means the statutory spelling lists for Years 3 and 4 and for Years 5 and 6, and the common exception words younger children learn by heart. February and rhythm follow no rule at all, which is the whole point of them, so no rule is used to place them.

Rare words are held back

A word can be easy to spell and still be one almost nobody uses. A frequency floor keeps those out, so a child is never asked for cote or pertussis on the grounds that they are short.

Words we take out

Words unsuitable for children are taken out by hand, and a check runs on every build that fails if one of them ever reaches a game. It runs over the word itself, over its plurals and endings, and over any word used to build another, so a word that is out cannot come back in through a longer one.

The school year picks which of these your child meets

The level is set once, by school year, and matched to that country’s curriculum. What each year covers is written out year by year in the curriculum guide, from Reception and Kindergarten up to Year 6.

What this is not

It is not the whole of English. A word that no teaching point reaches and no published list names is left out rather than guessed at, so plenty of perfectly good words are missing on purpose. Naming a curriculum or a research paper here says where a rule came from; it is not a claim that anyone has endorsed these games.

The statutory spelling lists come from the National Curriculum in England, English Appendix 1, published by the Department for Education. The age ratings come from Kuperman, Stadthagen-Gonzalez and Brysbaert (2012), “Age-of-acquisition ratings for 30,000 English words”.