With the proliferation of smart phones and tablet devices, the technology is fast trickling down to the youngest members of the family. It seems like a new, so-called ‘educational’ app comes on the market every day.

But no agency is making sure that an application labeled as "educational" really is -- or that it's appropriate for the age group it targets. That leaves many parents of preschoolers are in a quandary: to iPad or not to iPad? And what age is appropriate for a child to start swiping and tapping?

Marlene Acheson, director of the Pacific Beach Presbyterian preschool in San Diego, is in the "not to iPad" camp. She doesn't have computers, lap-tops or tablets in her classrooms because she believes they stop children from communicating with each other, and in some cases, their own language development slows. You don't need to talk when staring at a screen, she points out.

"As soon as the child spots that computer screen, creativity goes out the window," she said.

Acheson, who has been in early childhood education for over 40 years, is sticking to blocks and books.

But on a recent Wednesday afternoon, she allowed Frank Jensen, founder and CEO Binary Labs, to show kids a new iPad game he had created for preschoolers. Acheson said she was curious about what an iPad game could possibly teach.

In one of the games, chili peppers dance around the screen and the child has to try to pinch them with the thumb and pointer finger. If done correctly, the chili pepper disappears. In another game, the child has to draw a line with her finger from a dot to a star, which takes a lot of fine motor control for a preschooler.

The San Diego preschoolers got the hang of Jensen’s app pretty quickly. But Acheson said she's still keeping screens out of her preschool.

Jensen developed the chili pepper app after discovering his own daughter had a fine motor delay. The finger exercises the occupational therapist gave her were repetitive and boring. Which made Jensen wonder how to keep a preschooler interested enough to do them. And then the idea of an iPad app hit him.

“One of the unique things about the iPad is that it can detect all ten fingers individually,” Jensen said.  He said he consulted pediatric occupational therapists to develop an app that detects the individual input of fingers and their dexterity.

Practicing pinching, Jensen learned through his daughter’s therapy, strengthens critical muscles.

“What that relates to is the ability to hold a pencil," Jensen said. "It developed the "appropriate coordination and strength in those fingers which then translates into successful use of a pencil.”

But not all applications marketed to children go through rigorous testing or consultation with experts.

At least one researcher is finding that apps may not be as useful as they seem.

Georgetown University professor Rachel Barr wanted to find out whether tablet learning translates to real world learning. Barr’s team developed a puzzle game for a touch screen that could be replicated on the floor with actual blocks by toddlers aged 15-33 months. When the children were shown how to make a puzzle on a touch screen device, they could repeat it on their own. But they could not as easily do it with the blocks.

“Once we switched from the touch screen to the real object, so they had to go from the 2d world to the 3d world, we found that they learned a lot less and they were a lot less accurate,” she said. "Some of the laws of physics that apply in the real world don’t apply in the touch screen device.”

So while a parent might see their child successfully using an app, that doesn’t mean the child will be able to do a similar task in the real world.  She still needs an adult to show her how it translates from the screen to physical objects, like blocks.

And then there's the warning by the American Association of Pediatrics. In 2011, that group said children under 2 shouldn't be spending any time in front of a screen.

As a stay-at-home mother, Lisa Guernsey occupied her 18-month-old and three-year-old children with a screen when she needed to deal with someone on the phone, or cook dinner, or even just steal five minutes for a cup of coffee. Worried that she might be harming them, she began investigating the AAP's decree.

“It's a stretch to say that no matter what the content is that there is something sort of harmful about what’s coming through the screen," said Guernsey, who is also the New America Foundation’s Early Education Director. She published her findings in a book called Screen Time.

The AAP’s recommendations were based on evidence that infants and toddlers learn more from live human interaction than they do from passive TV watching. But there wasn’t hard evidence that proved a causal relationship between screen time and harmful effects on small children.

“If parents are talking with their children and co-viewing with their children then its a whole different ball of wax,” she said. That kind of screen time, rather than being harmful, might help a child learn.