It may be boring for parents - but reading the same book over and over again to children is the best way to develop their vocabulary.
Researchers at Sussex University have found that repetition is more likely to help them improve their reading skills.
"What we think is happening with reading is that each time a child hears the book, they are picking up new information," said psychologist Dr Jessica Horst, who conducted the research.
She added: "We know that children who watch the same television programme over and over again do better in comprehension tests afterwards."
The researchers devised an experiment with three-year-olds in which they were exposed to two new words to test the theory.
Each word was a made-up name for an unfamiliar object - such as a "sprock", a hand-held device for mixing food.
Over the course of a week, one group heard three different stories with the same new words. The second heard only one story with the words. Each contained a drawing of the new objects.
Those who had heard just one story were much better at remembering and recalling the new words when tested at the end of the week compared with those who had been read the three different stories.
"We know that the more books you have at home, the higher the academic achievement," said Dr Horst.
"But what we haven't understood is actually how that learning happens.
"This research shows that it's not the number of books but the repetition of each book that leads to the greater learning."
Margaret Morrissey, of the parents' pressure group ParentsOutloud, said: "To a degree I could go along with that. The most important thing is taking the time to read to your children every night in the first place."
She added: "It is important, too, to allow them to choose the story to read. If you do that, nine times out of 10 they will probably choose the same one."
However, she warned that it was imperative there were enough books in the home to allow the child a choice.
The research is by Dr Horst, Kelly Parsons and Natasha Bryan and is being published in Frontiers in Psychology later this month.
- INDEPENDENT
By Richard Garner