"Test-taking cements knowledge"

Taking a test . . . actually helps people learn, and it works better than a number of other studying techniques.

It works better than studying and it works better than concept mapping, which is described as "having students draw detailed diagrams documenting what they are learning . . . prized by many teachers because it forces students to make connections among facts."

The Purdue study supports findings of a recent spate of research showing learning benefits from testing, including benefits when students get questions wrong. But by comparing testing with other methods, the study goes further.
“It really bumps it up a level of importance by contrasting it with concept mapping, which many educators think of as sort of the gold standard,” said Daniel Willingham, a psychology professor at the University of Virginia. Although “it’s not totally obvious that this is shovel-ready — put it in the classroom and it’s good to go — for educators this ought to be a big deal.”
Howard Gardner, an education professor at Harvard who advocates constructivism — the idea that children should discover their own approach to learning, emphasizing reasoning over memorization — said in an e-mail that the results “throw down the gauntlet to those progressive educators, myself included.” 

Don't think of it as testing, think of it as "retrieval practice".  After reading a passage, students wrote an essay about the passage from memory, re-read it and then took a test on it.  This group of students scored higher than the other groups who studied or who concept mapped.  The writing seems to have been important, but the critical part was retrieving the information.  Why it works is unclear, but it is speculated that "by remembering information we are organizing it and creating cues and connections that our brains later recognize."

How can schools incorporate these new findings in a way that can raise achievement levels?  What can parents do?

To Really Learn, Quit Studying and Take a Test - NYT