Table 2.

Overview of the identified core themes in the definitions

	Educational activity	Structure	Timing	Repetition	Content	Educational tool	Learning outcomes
Plural definitions
Spaced learning (5)71, 75, 79, 82, 127	5/5	5/5	5/5	4/5	3/5	1/5	2/5
Spaced practice (2)57, 128	2/2	2/2	2/2	1/2	1/2		1/2
Retrieval practice (6)12, 59, 128, 129, 130, 131	6/6	1/6	3/6		1/6		2/6
Distributed practice (19)12, 46, 60, 67, 68, 73, 88, 91, 92, 93, 99, 101, 103, 104, 106, 110, 128, 132, 133, 134, 135	19/19	17/19	14/19	2/19	5/19		4/19
Spaced education (19)19, 20, 22, 23, 24, 27, 28, 29, 30, 34, 35, 36, 44, 47, 52, 53, 54, 78, 81, 85, 114, 136, 137	15/19	15/19	8/19	9/19	8/19	11/19	7/19
Single definition
Spaced approach72	X	X	X
Distributed training98	X	X	X
Spaced distribution34, 35, 36, 38	X	X	X	X
Distributed study138	X	X	X	X	X		X
Spaced repetition116	X	X	X	X	X		X
Automated spaced repetition18	X	X	X	X	X		X
Repeated practice68	X	X
Structured spaced training86	X	X
Interleaved practice21	X	X			X
Spaced training139	X	X					X
Interactive‐spaced education140	X	X		X	X	X	X
Space repetition learning45	X		X		X		X
Interval learning137	X		X	X	X
Interval training141	X	X	X	X
Repeated testing117, 118	X		X	X	X		X
Distributed method of learning105	X		X	X	X	X	X

In case of terms with plural definitions, only core themes recurrent in all definitions are indicated. The number of plural definitions is indicated for each term in brackets. This table only shows the terms with definitions (21 total). Terms identified without definitions were: Dispersed learning;50 Distributed learning;50, 60 Repeated retrieval practice;112 Spaced instruction;49 Spaced training;49 Spaced retrieval practice;66 Spaced studying,142 and Spaced testing.143