"My own child said to me years ago that there is absolutely no satisfaction in reading a book electronically, because you don't see the heft of what you have just managed to read.
"If a kid reads a 200 to 300-page book that's a really big achievement. But if you read electronically you don't see that. And also you don't see the cover every time you go to your book. You don't pick it up and instantly relate to the thing you are reading."
As for the books they are consuming, the Harry Potter series is back at No 1, followed by Roald Dahl's BFG and local favourite Hairy Maclary and Friends . Newcomers include the Tom Gates and Skulduggery Pleasant series. Enid Blyton classics The Magic Faraway Tree and the Famous Five have made comebacks.
Mackenzie suspects parents have a strong influence.
"I think most parents who are readers and want their kids to be readers try to pass on to them things they loved when they were younger."
Dahl's books were the kind passed on from generation to generation.
"So are things like Dr Seuss. Parents buy those books because they know them."
• The Whitcoulls Kids' Top 50 list: