THE GREAT GRAMMAR BOOK Written by Kate Petty Illustrated by Jennie Maizels Paper engineering by Damian Johnson Bodley Head Pounds 12.99. THE COMPLETE CASTLE By Nick Denchfield and Steve Cox Macmillan Children’s Books Pounds 12.99

Fourteenth-century medical students learned anatomy from flap books, and Inside the Body continues the time-honoured tradition. A punched hole allows the book to be hung open against a classroom wall, producing an 80cm x 30cm vertical spread with a full-length human frame on each double page. Readers can probe, flap by flap, ever deeper beneath the skin.

As ever with Dorling Kindersley, the page design is arresting, though sometimes there are too few clearly marked connections between diagrams and text. A note tells you that the Achilles is “the longest tendon in your body”, but you might need help to find it on the diagram.

The book may be most useful as a graphic reference; for example, the uterus opens out in stages to show a foetus at three-monthly intervals. A CD-Rom would make for more sequential learning, while the classic The Human Body by Jonathan Miller and David Pelham draws the reader into the working body more dynamically because the movement and depth of its three-dimensional models link with clearly annotated paragraphs.

Open House presents seven dwellings over the centuries, from a Roman street to a Wild West store. You lift the 90 or more flaps to reveal cameo activities. There are intriguing details to discover - a cowboy secretes some cards beneath the saloon table - though the book tries too hard to appeal to a notional 1990s child.

Some flaps expose lavatorial activity; a servant ruminates on a lofty privy jutting out beneath the battlements of a Scottish tower, while his faeces hurtle to a dung heap below - where a labourer, kerchief over his nose, shovels away.

There are few links to be made between the scenes. If the houses were caught at a moment in their history (a royal visit, an attack) linking the different vignettes, there would be a stronger invitation to make connections, to develop a narrative. It needs this quality of engagement to preclude exploring fingers flipping one flap, then another, then another, hardly pausing on the brief notes on the reverse.

In the best movable books, the movement is integral to the creation of meaning in the reader’s head. The Great Grammar Book measures up to this yardstick, although it may not quite be the complete answer (as the publicity implies) to such headlines as “British youth among least literate in Europe”. Beneath ingenious paper engineering lurks a grammar formal enough to satisfy most traditionalists.

First, Nicola Noun, a teacherly cat, brightly informs us that Nouns are Naming Words. A green worm named Alan Adjective tells us, “I describe things”, and so we go on by way of Anne Adverb, Percy Pronoun, Polly and Paul the plural parrots, and so on.

Vera Verb shouts, “Hi! Don’t stop! Keep moving! Verbs are doing words!” She is not much into feeling or indeed being, but maybe that’s the only place to start.

Rotate the picture on Vera’s page and you make divers dive, fish fly, leap and blow. You can play Heads, Bodies and Legs with multi-layered flaps to concoct bizarre creatures - an adjective to every flap. A single pull of a tab capitalises and punctuates an entire paragraph. You might take Pipsqueak the dog on his string lead for a walk under the bridge, around the tree and down the burrow on the preposition page.

Bodley Head is wise to recommend the book for “home learning” since it probably needs a friendly mediating adult to sort out possible confusions and to persuade a child that there’s some value in all this labelling. Juniors in a classroom might be more interested in exploring how pop-ups, rather than nouns, worked.

To the adult eye, the pages are numbingly busy, seeming to fight against learning something which is essentially orderly. But children accustomed to the freneticism of Saturday morning television may not find this a problem.

The Complete Castle promises a “three-dimensional adventure”. The package includes a short paperback with punch-out figures of jousting knights, ladies, villeins and the rest, along with a cardboard castle to be swiftly erected on a landscape “mat”. The basic idea sounds hopeful - to embed historical information in a story about the Lord of the Castle, Baron Swarthy. But the narrative never gets going and the characters are devoid of personality, so the information has little context and becomes intrusive. Then, in a surprising shift in narrative direction, Able Grout the armourer is drowned. Who is the murderer? (And do we care?) The crime is to be “solved” by working out which suspect “tells the most lies” - you check by looking inside the model of the castle (you have to lift it up from its mat, thus losing the illusion of the model and imperilling the entire edifice). The problem is that the lies are pointless - the wrong number of hel-mets on the floor and so on - and absolutely nothing to do with how Grout comes to be upside down in the well. Any child sees enough police dramas to know you don’t catch murderers (who tend to be good at telling lies anyway) by assessing their numeracy skills.