There's no such thing as too much education, right?
As iPads have become ubiquitous, companies have rushed to develop educational games that teach math, physics and even urban planning.
But many of these games are only "educational" in the loosest sense of the term, and almost none have been tested in rigorous studies, say scientists. The ones that have been tested show modest results.
"It turns out to be pretty hard to make games or content that are better than school," said Jeremy Roschelle, director of the Center for Technology in Learning at SRI International, a nonprofit research institute in Menlo Park, Calif.
"Edutainment" apps have flooded the market. Apple dedicates a whole section to educational apps, and the group MinecraftEdu is leveraging the highly addictive game "Minecraft" to give lessons on environmental sustainability and gravity, and even to teach English.
But despite the flood of products, there's little evidence that such games do much to improve cognitive ability or general test scores. That's because practicing a game may hone a narrow set of skills needed to excel in the particular game, but those skills don't extend to broader concepts or general abilities.
"If your outcome measure is a state test at the end of the year, you're going to find no games move that," Roschelle told LiveScience, referring to improving a person's test score.
Several studies have shown that mobile and other games make children more motivated to learn a topic. Though the kids don't necessarily learn more initially, they may retain more information about a particular period of time after playing a history-based, immersive reality game such as "Civilization."
And virtual world simulation games that encourage a community to solve a problem, such as identifying and stopping an epidemic's outbreak, might teach kids problem-solving skills in certain arenas, Roschelle said.
For parents, deciding whether a game makes the cut can be tricky.
In the absence of evidence that an educational game works, parents should assume it doesn't, Roschelle said. "If you don't have a research study, I would guess that a game is not going to produce an outcome," he said.
And since evidence of educational games' effectiveness is so limited, it may not even be worth redirecting kids from "Doom" or "Grand Theft Auto" to educational tablet games, Roschelle said.
"I don't really think it's going to get them into Harvard," he said.
Most educational games should be viewed as a learning side dish — something that doesn't suck time from core learning activities like schoolwork. A game that teaches math is probably no substitute for going to math class or doing algebra homework, for instance.
On the other hand, there's nothing inherently bad about the games, either.
"If your kid is making good grades and has friends and has interests, let 'em play games as much as they want," Roschelle said.