retrieval practice or spaced learning

One of the 4 techniques, associated with learning gain, used by the timely practice system - with the aid of the timely practice app.

In a nutshell:

learning performance improves if study sessions are separated in time, or spaced out, rather than blocked together.

Teaching a topic and then requiring learners to practise that learning only during that lesson or that unit is blocked learning.

Teaching and then requiring learners to practise that learning for short periods of time throughout the year is spaced learning.

Spaced learning by analogy

There is an exponential loss of memory unless information is reinforced.

Exponential loss of memory is like a balloon which will gradually shrink over time.

Acts of revision should be spaced in gradually increasing intervals. This is called increasing interval retrieval practice or spaced repetition.

Learning using spaced repetition is like a person creating a path on a lawn. Each time the person walks the path, the path becomes a little deeper and easier to follow.

After each revision the memory retention lasts longer, the loss of memory is slower.

After a while the path is so deep that it rarely needs to be walked yet will remain clear and its use becomes second nature, it can be followed without thought.

SRS Learning says

That spaced learning works doesn't seem to be in doubt, but to manage spaced learning in the classroom the teacher will need help to:-

store suitable questions,
make setting and assessing learners' work faster,
hold data about who needs to review what and when.

The timely practice app is a tool to help the teacher do all of the above.

Spaced learning explained by graph

See the mp4 below on how timely practice applies Rohrer and Taylors' research

and increasing interval retrieval practice or spaced repetition system (SRS) which explains Ebbinghaus' forgetting curve and how SRS makes use of this to improve learners' memories.

What educational researchers say about how it works

“One of our main points is that learners need to practice retrieving information as a regular part of studying. This way they will have the information at their mental fingertips for use when they need it. Retrieval practice at spaced intervals also slows forgetting. Active retrieval is critical for long-term retention.”
Make it Stick: The Science of Successful Learning, Peter C Brown, Henry L Roediger and Mark A McDaniel

Active recall is a far superior method of learning than simply passively being exposed to information.
Jeffrey D. Karpicke (2011) New York Times http://www.nytimes.com/2010/09/07/health/views/07mind.html and Retrieval Practice Produces More Learning than Elaborative Studying with Concept Mapping http://science.sciencemag.org/content/early/2011/01/19/science.1199327.abstract and Agarwal et al (2008) “Examining the Testing Effect with Open- and Closed-Book Tests” where closed book tests with feedback were found to be most beneficial.
... this (retrieval practice or quizzing) is one of the most powerful learning tools we have.”
Dr. Roediger http://www.nytimes.com/2010/09/07/health/views/07mind.html and see http://psych.wustl.edu/memory/Roddy%20article%20PDF's/BC_Roediger%20et%20al%20(2011)_PLM.pdf for the 10 benefits of testing.

When learners see a list of problems, all of the same kind, they know the strategy to use before they even read the problem [that's] like riding a bike with training wheels. [With mixed practice] each problem is different from the last one, which means kids must learn how to choose the appropriate procedure — just like they had to do on the test.
http://www.nytimes.com/2010/09/07/health/views/07mind.html?_r=0 from Rohrer, D. (2009). The effects of spacing and mixing practice problems. Journal for Research in Mathematics Education, 40, 4-17

What educational researchers say about why it works

Cognitive scientists see testing itself - or practice tests and quizzes - as a powerful tool of learning, rather than merely assessment. The process of retrieving an idea ... seems to fundamentally alter the way the information is subsequently stored, making it far more accessible in the future.
Nate Kornell http://www.gwern.net/Spaced%20repetition?2 and http://www.nytimes.com/2010/09/07/health/views/07mind.html

The harder it is to remember something, the harder it is to later forget, researchers call this “desirable difficulty”. The more mental sweat it takes to dig it out, the more securely it will be subsequently anchored.
Benedict Carey , New York Times http://www.nytimes.com/2010/09/07/health/views/07mind.html

"A theory of retrieval difficulty proposed by Bjork and Bjork (1992). They argued that information in memory might be characterized in terms of two strengths:
storage strength,
which refers to a permanent property of the information that determines long-term retention, and
retrieval strength,
which refers to the momentary accessibility of the information.
In their theory when retrieval strength is high and information is easily accessible, the retrieval of that information produces small increments in storage strength. In contrast, lower retrieval strength and more difficult retrieval produce greater increments in storage strength and thereby promote long-term retention, assuming the item can be retrieved.
A. Healy, S. Kosslyn, & R. Shiffrin (Eds.), From learning processes to cognitive processes: Essays in honor of William K. Estes (Vol. 2, pp. 35–67). Hillsdale, NJ: Erlbaum. https://pages.wustl.edu/files/pages/imce/memory/2008_agarwal.pdf and Bjork, R. A., & Bjork, E. L. (1992). A new theory of disuse and an old theory of stimulus fluctuation. https://bjorklab.psych.ucla.edu/wp-content/uploads/sites/13/2016/07/RBjork_EBjork_1992.pdf

Meta-analysis (educational research) says:

"Since the spacing effect was first discovered by Ebbinghaus in 1885, research has consistently shown that learning performance improves if multiple study sessions are separated in time (or “spaced”) rather than massed together. The effect occurs for adults, pre-schoolers and infants, and primary and secondary school children. A brain imaging study suggests the spacing effect in verbal learning is due to enhanced maintenance rehearsal (i.e. additional thinking about the material) in spaced, relative to massed presentations."

https://v1.educationendowmentfoundation.org.uk/uploads/pdf/NSED_LitReview_Final.pdf (page 29 to 30)

A blog from an expert

Robert Bjork - spacing improves long-term retention

storage strength,	which refers to a permanent property of the information that determines long-term retention, and
retrieval strength,	which refers to the momentary accessibility of the information.