SECONDARY school pupils in Scotland are not choosing challenging enough books to read in their spare time, according to a literacy study.

The survey found there was little difference between reading habits in primary and secondary with book difficulty declining as children got older.

Book by David Walliams such as Gangsta Granny and Jeff Kinney’s Diary of a Wimpy Kid series both dominated the top ten books in both primary and secondary sectors.

Renaissance UK, the literacy and assessment company who conducted the study, said many 16-year-olds sitting National 4 and 5 qualifications had the reading ability of a 13-year-old or lower.

The company went on to call for more dedicated time for reading in secondary school.

Keith Topping, professor of educational and social research at Dundee University, who analysed the results, said the drop-off could harm pupils’ ability to understand exam papers.

He said: “To avert a further slide in literacy levels in secondary schools, pupils should be encouraged to push themselves to read more difficult books.

“By their teenage years pupils are more likely to take advice from their friends and peers than their teachers and parents about the types of books they should be reading.

“With this in mind, teachers could encourage them to talk more openly about what they are reading and make appropriate suggestions to their classmates.”

The study found an emphasis on literacy development in primary schools which sees pupils typically read more advanced books for their age, but progress largely stops when they reach secondary school with the difficulty of books falling as pupils get older.

The decline exists among both boys and girls and across the UK as a whole,

Renaissance UK managing director Dirk Foch said an improvement could be made by reading for just 15 minutes a day.

He said: “The vast majority of primary schools place an emphasis on developing pupils’ literacy skills, but this is rarely continued once pupils go to secondary school.

“This makes maintaining literacy levels among teenagers a persistent challenge for teachers and policy makers.

“The fall in teenagers’ reading ages is striking. By the time many come to sit their National 4 and 5 examinations, many will have a reading age of 13 or less, meaning that they could even struggle to comprehend their exam papers.”

Mr Foch said all secondary school teachers should build dedicated reading into the timetable to avert a further fall in literacy levels among young people.

The Renaissance study looked at the reading preferences of 29,524 pupils across Scotland as part of the UK-wide What Kids are Reading Report.

First Minister Nicola Sturgeon has already launched a Reading Challenge to promote literacy and “reading cultures” in schools, libraries and communities.