Picture books for pre-schoolers are usually read by adults to the child. They are often landscape so that the child and parent can share the book. Even households that have few books will often have some picture books.
Even today picture books are expensive to produce so they must be easily translatable into other languages. Therefore, rhyming texts are not usually accepted. There are of course exceptions, including Julia Donaldson's work.
For practical reasons to do with printing, picture books are usually 32 or 28 pages long, including endpapers. That is, 24 or 28 pages - or 12 or 14 double spreads.
The story must be contained in this quite rigid format.
There will be a lot of repetition.
There is a change in pace / rhythm about 2/3 to 4/5 of the way through the story – rarely exactly ¾ of the way through.
There is sometimes a joke for adults – but not at the expense of the child.
The pictures contain more of the story.
The font is adult-friendly e.g. Times new Roman which is actually nightmare for new readers; the serifs are confusing and the 'a' and 'g' are difficult.
The language may be surprisingly sophisticated.
Take a look at some picture books. You might also like to study some well-known ones:
Julia Donaldson's Room on the Broom
Judith Kerr's The Tiger Who Came to Tea
Eric Carle's The Hungry Caterpillar
Maurice Sendak's Where the Wild Things Are
Change of pace
How the pictures work. Look as well at the balance of pictures. Do some have no text? Which are on single spreads and which on double? Why? Are there multiple pictures on some pages? Why? How effective is this?
Look at how white space is used? What leads the eye from one page to the next?
Is there a joke for the adults?
What about the language and the font?
Now your turn
Have a go at producing a picture book text. First write it as a continuous story. Then spread it across the 24 or 28 pages. Think about how the pictures will work.