How to Promote Lasting Learning in Schools

Meaningful Learning and Desirable Difficulties

Basically, two broad lines of theory and associated research are devoted to lasting learning, the conditions that foster lasting knowledge, and the underlying cognitive processes. The first, classical approach posits that meaningful learning is the key to creating lasting knowledge. In educational psychology, the work by Ausubel (1963) has laid the foundations for this approach by pointing out the pivotal role of prior knowledge for learning new information and the necessity that learners make sense of what they are learning, as opposed to pursuing rote learning, that is, simply memorizing information. Ausubel also pointed out that meaningful learning is an active process, implying that learners can employ cognitive strategies beyond rote rehearsal to assist and benefit their comprehension and learning skills. These basic ideas were subsequently taken up and developed further in various theoretical and instructional approaches, such as generative and active learning (Fiorella & Mayer, 2016; Wittrock, 1974), and have become the mainstream view on learning in educational psychology and the educational sciences. The notion of meaningful learning also directly informs a variety of specific instructional methods, such as using advance organizers, concept mapping, or teaching and prompting learning strategies.

Many experiments have demonstrated unequivocally and for various types of information (e. g., verbal and pictorial information) that learned information is forgotten fast (often on a time scale of a few minutes) if it is not meaningfully processed, that is, well comprehended and integrated with prior knowledge (for examples of classical experiments, see Kintsch et al., 1990; Mandler & Ritchey, 1977). Moreover, meta-analytic reviews have shown for a variety of broad instructional approaches and specific instructional methods that meaningful learning can effectively improve learning in school settings. For instance, meta-analytic evidence is available for the effectiveness of learning strategy instruction (Donker et al., 2014), guided inquiry-based learning (Lazonder & Harmsen, 2016), reciprocal teaching (Rosenshine & Meister, 1994), concept mapping (Schroeder et al., 2018), and advance organizers (Stone, 1983) (see also the meta-meta-analysis by Hattie, 2009, Ch. 9 and 10, for further examples). It should be noted, though, that most of the available research has not specifically addressed whether and how instruction informed by the notion of meaningful learning fosters lasting learning.

The second major approach devoted to lasting learning has become known as desirable difficulties in learning (Bjork, 1994). These are conditions in the instructional setting that make the learning process more difficult, both subjectively and objectively in terms of increasing cognitive load, but that foster long-term retention by stimulating cognitive processes conducive to lasting learning. Evidently, not all difficulties in learning are desirable. Most conditions that make learning more difficult merely impose extraneous cognitive load on the learner. For instance, badly designed learning materials, background noise, or presenting information that presupposes prior knowledge that students do not possess do not qualify as desirable difficulties.

Applied memory research has identified various types of conditions that may, at least under certain circumstances, fulfill the criteria for desirable difficulties. These include having learners generate information themselves instead of presenting it (generation effect, McDaniel et al., 1988; Slamecka & Graf, 1978), varying the context between learning sessions instead of keeping it constant (Smith et al., 1978), or intentionally reducing the processing fluency during learning (Diemand-Yauman et al., 2011). Among the desirable difficulties that have attracted the most interest among researchers in educational psychology and the learning sciences are retrieval practice, spacing, and interleaving:

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  Retrieval practice refers to the use of tests as learning opportunities, which are assumed to be more effective than restudying for long-term retention. This so-called testing effect has been demonstrated in many studies based on different materials, from simple verbal materials (Karpicke & Roediger, 2008) to contents of expository texts (e. g., Roediger & Karpicke, 2006), both in the laboratory and in classroom experiments (for meta-analyses, see Rowland, 2014; Yang et al., 2021). Compared to restudying the same materials, retrieval practice requires cognitive effort and potentially reveals knowledge gaps, which from the learner’s perspective are likely to increase the difficulty of the technique. For example, students tend to believe that rereading is a more effective learning strategy than self-testing, although the evidence suggests the opposite (e. g., Kornell & Son, 2009).
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  Spacing refers to the distribution of the total available learning time over several shorter units instead of massing it in one unit (or a few longer units). Spacing is probably the best-researched desirable difficulty (for a meta-analytic review, see Cepeda et al., 2006). The effectiveness of spacing for long-term learning outcomes has been established for different time scales and different contents such as verbal materials, cognitive skills, or motor skills. Importantly, positive evidence exists only for learning that involves repetition, such as spacing repeated presentations of the same information or spacing practice phases with identical or similar exercises. In such situations, spacing can benefit lasting learning, especially with longer (but not too long) intervals between learning sessions. Like retrieval practice, spaced learning is often experienced as more difficult than massed learning, as forgetting occurs between learning sessions and relearning proceeds less fluently after a delay. In line with this reasoning, students often (although not always) prefer massed over spaced learning (for a review, see Son & Simon, 2012).
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  Interleaving refers to the sequence of exemplars in inductive learning settings, for instance, when concepts or principles are derived from a set of observations or case descriptions or by practicing tasks that require different rules to solve them. In interleaved learning, the exemplars corresponding to different categories or rules are presented in an interleaved instead of a blocked fashion. Interleaved learning seems to play out its advantages if the discrimination between exemplars is crucial for learning, but positive evidence is available only for some types of materials, such as visual stimuli and mathematical tasks (for meta-analytic results, see Brunmair & Richter, 2019). Moreover, experiments that have specifically addressed whether interleaving fosters lasting learning are still scarce, and the available findings are inconclusive. Studies have shown that learners perceive inductive learning with a blocked presentation of exemplars as more successful than learning in an interleaved fashion, even if the actual learning outcomes follow the opposite pattern (e. g., Kornell & Bjork, 2008).

Promises and Challenges of Implementing Desirable Difficulties in Educational Contexts

The notion of desirable difficulties has gained considerable popularity in recent years, among researchers in cognitive and educational psychology and among educational practitioners. The increased interest may partly be because of the counterintuitive nature of the claim that making learning more difficult benefits learning. Another likely factor is the sustained effort of proponents of desirable difficulties to emphasize the relevance of desirable difficulties for education and to market the approach to educational practitioners (for examples, see the book by Brown et al., 2014; or the website https://www.learningscientists.org/). Most importantly, the desirable difficulties approach is backed up by strong experimental evidence, mostly from lab studies. For retrieval practice, spacing, and interleaving, meta-analyses exist that report at least medium overall effects of each desirable difficulty (Brunmair & Richter, 2019; Rowland, 2014; Yang et al., 2021), suggesting that these desirable difficulties have great potential for fostering lasting learning in educational contexts.

However, for both conceptual and empirical reasons, it also seems clear that simply transferring the learning principles into the classroom might not work in all cases. Empirically, the evidence for the effectiveness of desirable difficulties in the classroom is mixed and still scarce, especially for interleaving and spacing. For retrieval practice, many classroom studies underline the potential of practice tests for learning, but many of these studies were based on nonexperimental designs or used a “no-activity” control group (Yang et al., 2021). Moreover, many studies focused on simple recall and recognition of information and neglected comprehension and transfer crucial for school learning. The available empirical evidence and questions regarding its scope and validity are discussed in more depth in the contributions by Roelle et al. (2022) for retrieval practice, by Ebersbach et al. (2022) for spacing, and by Richter et al. (2022) for interleaving.

Theoretically, explanatory accounts of desirable difficulties help us to understand the basic memory processes that are important in educational contexts as well, such as how retrieval practice contributes to the consolidation of memories (Karpicke & Roediger, 2008) or how contextual variability increases the chances that learned information is passively cued and retrieved at a later test (Smith et al., 1978). But the more complex types of learning that occur in the classroom require a broader theoretical perspective that includes how such basic processes interact with meaningful processing. For instance, existing accounts of retrieval practice fail to specify the role of initial comprehension of the learning materials, which might be a crucial precondition for the effectiveness of retrieval practice with complex materials such as expository texts (Rummer & Schweppe, 2022). Likewise, concepts from theories of meaningful processing are needed to explain how retrieval might foster not only memory of explicit information but also transfer (Pan & Rickard, 2018). With regard to spacing, the deficient processing account posits that distributed practice elicits deeper processing than massed practice (e. g., Hintzman, 1974). But to specify the meaning of “deeper processing” of a scientific explanation, a mathematical task, or other contents typically encountered in school, researchers need to turn to theories of meaningful processing.

As a final example, to be effective in educational contexts, which usually require considerable self-regulated learning, desirable difficulties must stimulate learners to actively process information during learning. Therefore, instructional measures that guide and support learners to use relevant strategies in the right situations, for example, comparison strategies in interleaved mathematics learning (Ziegler & Stern, 2016), are likely to boost the effectiveness of desirable difficulties. Again, these questions are discussed in more depth in the other articles in this special issue.

Toward a Theory of Lasting Learning in Educational Contexts

To return to the questions raised at the beginning, there is some evidence that students can retain a considerable proportion of the knowledge acquired in school, provided they receive a sufficient dose of instruction. Thus, school instruction seems to be suitable, at least to some extent, to create lasting knowledge, although more (and better controlled) longitudinal studies would be beneficial for further clarification. Regarding the question of what teachers should do to foster lasting learning, the approaches of meaningful learning and desirable difficulties have both yielded principles and instructional methods that might contribute to this goal. However, a theoretical integration of the two complementary approaches seems to be an important objective for psychology and the learning sciences. Instead of holding “horse races” (Salomon, 2002) and asking which of the two approaches performs better, as was done in the past (e. g., Karpicke & Blunt, 2011; Rummer et al., 2017), we should move on to the question of how ideas of meaningful learning and desirable difficulties can be fruitfully combined to create lasting knowledge. For example, research should examine to what extent the “deeper processing” that is supposedly instigated by desirable difficulties overlaps with or is distinct from those processes described in theories of meaningful learning. A related issue is determining the roles of strategic and routine learning processes for the effectiveness of desirable difficulties. If strategic processes play a role, students could be taught relevant learning strategies to make the most of desirable difficulties. Likewise, instructional support might be effective in assisting students in using desirable difficulties constructively.

To examine these issues, we need experimental intervention studies in schools that assess learning outcomes shortly after learning and at delays of several weeks or longer. Such studies are ambitious and costly in terms of time and other resources and have rarely been conducted in the past. But the investment is likely to pay off. Longitudinal experimental studies in the classroom promise to significantly advance the theoretical understanding of lasting learning and how it can be effectively implemented in the classroom.