There is an on-going debate over which is better: paper books or e-books. I prefer paper books because of their tangibility and sentimentality; however, e-books are better for mobility and practicality. It’s an even split for most, but a new debate has arisen between whether reading apps or paper books are better for kids.
A study was conducted by researchers at Temple University’s Infant Laboratory in Philadelphia and Erikson Institute in Chicago to answer this question. They found that traditional books give parents and preschool age children a more positive shared reading experience than reading apps.
When parents and children read e-books together, the parents tend to give directions and instructions rather than talk about the content of the book. This interrupts the learning process and confuses the story in the child’s mind. Directions and steps within the e-book program can have a similar effect because they too interrupt the learning process. 
“The kids ended up with 'a jumbled version of the story in their brains,' said Julia Parish-Morris, one of the leaders of the study at Temple University and now post-doctoral researcher in pediatrics at the University of Pennsylvania. 
“It turned out that reading electronic books became a behaviorally oriented, slightly coercive parent-child interaction as opposed to talking about the story, relating it to their child's life, or even talking about the book's pictures or text," Parish-Morris said. "Parents were under the impression that when you are sitting down with a book, you are supposed to read it," she added. 
Vanderbilt University also conducted a study, led by Gabrielle Strouse, which showed how a parent talked to the child while using the e-reader also made a difference. Strouse said “it appeared that parents had to be trained on how to ask questions and prompt their children to talk about the video story, as it didn’t come naturally with the electronic version." 
"We shouldn't use e-books to replace traditional books, and we shouldn't expect them to do something that they don't,” Collins said. “They're not substitutes for a human being." 
E-books take away from the interaction between parent and child that usually occurs with traditional books. Paper books allow parents to be more involved with their child, while e-books do all the reading and directing. Parents talk with their children, ask questions, and relate the book's story to real life when reading a traditional book.
When using e-books, most of the interaction is simple direction; they tell the child what to do, when to push a button, or instruct them to be careful. A traditional book can also take a bit more wear and tear; parents are not as worried about a ten-dollar paper book in the hands of the three-year-old as they are a one hundred dollar tablet.
It’s possible that for an older kid who already knows how to read, there would not be as striking of a difference in the learning process between e-book and traditional book. If the child is still learning, however, the research shows that traditional books are the better way to go.
Sources:  http://ideas.time.com/2011/12/20/why-ereading-with-your-kid-can-impede-learning/