Applying the science of learning to medical education

Medical Education 2010: 44 : 543–549 Objective The goal of this paper is to examine how to apply the science of learning to medical education. Science of Learning The science of learning is the scientific study of how people learn. Multimedia learning – learning from words and pictures – is particularly relevant to medical education. The cognitive theory of multimedia learning is an information‐processing explanation of how people learn from words and pictures. It is based on the idea that people have separate channels for processing words and pictures, that the capacity to process information in working memory is limited, and that meaningful learning requires appropriate cognitive processing during learning. Science of Instruction The science of instruction is the scientific study of how to help people learn. Three important instructional goals are: to reduce extraneous processing (cognitive processing that does not serve an instructional objective) during learning; to manage essential processing (cognitive processing aimed at representing the essential material in working memory) during learning, and to foster generative processing (cognitive processing aimed at making sense of the material) during learning. Nine evidence‐based principles for accomplishing these goals are presented. Conclusions Applying the science of learning to medical education can be a fruitful venture that improves medical instruction and cognitive theory.     

The facilitative effects of glucose ingestion on memory retrieval in younger and older adults: is task difficulty or task domain critical?

The ingestion of a glucose-containing drink has been shown to improve cognitive performance, particularly memory functioning. However, it remains unclear as to the extent to which task domain and task difficulty moderate the glucose enhancement effect. The aim of this research was to determine whether boosts in performance are restricted to particular classes of memory (episodic v. semantic) or to tasks of considerable cognitive load. A repeated measures (25 g glucose v. saccharin), counterbalanced, double-blind design was used with younger and older adults. Participants performed a battery of episodic (e.g. paired associate learning) and semantic memory (e.g. category verification) tasks under low and high cognitive load. Electrophysiological measures (heart rate and galvanic skin response) of arousal and mental effort were also gathered. The results indicated that whilst glucose appeared to aid episodic remembering, cognitive load did not exaggerate the facilitative effect. For semantic memory, there was little evidence to suggest that glucose can boost semantic memory retrieval even when the load was manipulated. One exception was that glucose facilitated performance during the difficult category fluency task. Regardless, the present findings are consistent with the domain-specific account in which glucose acts primarily on the hippocampal region, which is known to support episodic memory. The possible contribution of the hippocampus in semantic memory processing is also discussed.     

Gaze‐down endoscopic practise leads to better novice performance on gaze‐up displays

Objectives It is well known that precision skills are best learned when they are practised in the sensorimotor context that is present when performance is most important. However, a particular skill may vary with respect to the sensorimotor context in which it is performed. Certain sensorimotor variations can make a task more or less complex than others. Recent accounts of skill learning describe how task difficulty can be manipulated to provide optimised challenges to progress learners beyond their current level of expertise. This study tests the idea that simplified practise contexts lead novice learners to acquire skill proficiency that is more generalisable to new contexts. Methods We present a learning experiment in which the performances of novices who acquired a set level of proficiency in the endoscopic pots‐and‐beans task through performance‐based practise using a gaze‐up endoscopic monitor arrangement were compared against the performances of novices who acquired an equivalent level of proficiency using a simplified gaze‐down arrangement. Participants returned after 1 week for retention and transfer testing. Results Time and accuracy analyses revealed that participants in both training groups improved significantly over the practise protocol and maintained this performance after a period of retention. However, the comparisons of the visual display transfer performances (i.e. on the gaze‐up arrangement) of the gaze‐down trainees against the retention performances (i.e. also on the gaze‐up arrangement) of their gaze‐up counterparts and vice versa revealed that gaze‐down trainees made fewer errors in both performance contexts (F_1,16 = 7.97, p = 0.01 and F_1,16 = 57.05, p = 0.04, respectively). Conclusions These findings highlight the benefits associated with using simplified sensorimotor practise contexts for novice learners. Beginners will learn best from simplified practise because it allows them to develop good movement strategies for dealing with potential error without being overwhelmed by task complexity.     

Theoretical perspectives in medical education: past experience and future possibilities

CONTEXT: Pedagogical practices reflect theoretical perspectives and beliefs that people hold about learning. Perspectives on learning are important because they influence almost all decisions about curriculum, teaching and assessment. Since Flexner's 1910 report on medical education, significant changes in perspective have been evident. Yet calls for major reform of medical education may require a broader conceptualisation of the educational process. PAST AND CURRENT PERSPECTIVES: Medical education has emerged as a complex transformative process of socialisation into the culture and profession of medicine. Theory and research, in medical education and other fields, have contributed important understanding. Learning theories arising from behaviourist, cognitivist, humanist and social learning traditions have guided improvements in curriculum design and instruction, understanding of memory, expertise and clinical decision making, and self-directed learning approaches. Although these remain useful, additional perspectives which recognise the complexity of education that effectively fosters the development of knowledge, skills and professional identity are needed. FUTURE PERSPECTIVES: Socio-cultural learning theories, particularly situated learning, and communities of practice offer a useful theoretical perspective. They view learning as intimately tied to context and occurring through participation and active engagement in the activities of the community. Legitimate peripheral participation describes learners' entry into the community. As learners gain skill, they assume more responsibility and move more centrally. The community, and the people and artefacts within it, are all resources for learning. Learning is both collective and individual. Social cognitive theory offers a complementary perspective on individual learning. Situated learning allows the incorporation of other learning perspectives and includes workplace learning and experiential learning. Viewing medical education through the lens of situated learning suggests teaching and learning approaches that maximise participation and build on community processes to enhance both collective and individual learning.     

Applying the cognitive theory of multimedia learning: an analysis of medical animations

Context Instructional animations play a prominent role in medical education, but the degree to which these teaching tools follow empirically established learning principles, such as those outlined in the cognitive theory of multimedia learning (CTML), is unknown. These principles provide guidelines for designing animations in a way that promotes optimal cognitive processing and facilitates learning, but the application of these learning principles in current animations has not yet been investigated. A large‐scale review of existing educational tools in the context of this theoretical framework is necessary to examine if and how instructional medical animations adhere to these principles and where improvements can be made. Methods We conducted a comprehensive review of instructional animations in the health sciences domain and examined whether these animations met the three main goals of CTML: managing essential processing; minimising extraneous processing, and facilitating generative processing. We also identified areas for pedagogical improvement. Through Google keyword searches, we identified 4455 medical animations for review. After the application of exclusion criteria, 860 animations from 20 developers were retained. We randomly sampled and reviewed 50% of the identified animations. Results Many animations did not follow the recommended multimedia learning principles, particularly those that support the management of essential processing. We also noted an excess of extraneous visual and auditory elements and few opportunities for learner interactivity. Conclusions Many unrealised opportunities exist for improving the efficacy of animations as learning tools in medical education; instructors can look to effective examples to select or design animations that incorporate the established principles of CTML.     

An experimental study on the effects of a simulation game on students’ clinical cognitive skills and motivation

Simulation games are becoming increasingly popular in education, but more insight in their critical design features is needed. This study investigated the effects of fidelity of open patient cases in adjunct to an instructional e-module on students’ cognitive skills and motivation. We set up a three-group randomized post-test-only design: a control group working on an e-module; a cases group, combining the e-module with low-fidelity text-based patient cases, and a game group, combining the e-module with a high-fidelity simulation game with the same cases. Participants completed questionnaires on cognitive load and motivation. After a 4-week study period, blinded assessors rated students’ cognitive emergency care skills in two mannequin-based scenarios. In total 61 students participated and were assessed; 16 control group students, 20 cases students and 25 game students. Learning time was 2 h longer for the cases and game groups than for the control group. Acquired cognitive skills did not differ between groups. The game group experienced higher intrinsic and germane cognitive load than the cases group (p = 0.03 and 0.01) and felt more engaged (p < 0.001). Students did not profit from working on open cases (in adjunct to an e-module), which nonetheless challenged them to study longer. The e-module appeared to be very effective, while the high-fidelity game, although engaging, probably distracted students and impeded learning. Medical educators designing motivating and effective skills training for novices should align case complexity and fidelity with students’ proficiency level. The relation between case-fidelity, motivation and skills development is an important field for further study.     

Hospital doctors and their schemas about appropriate prescribing

OBJECTIVES: To investigate cognitive schemas and schema systems used by hospital doctors to influence prescribing, particularly in terms of making appropriate prescribing decisions, and to compare the numbers and content of schemas between doctors with different levels of experience. DESIGN: Qualitative interviews with a purposively selected sample. PARTICIPANTS AND SETTING: Seven pre-registration (PRHOs) and 5 senior house officers (SHOs) and 5 consultants from a range of medical specialties in a teaching hospital. RESULTS: The qualitative analysis of the themes and patterns explored during the interviews indicated that all doctors articulated schemas that influenced their behaviour. The junior doctors seemed to have simplistic schemas, with interdoctor agreement; the consultants appeared to have more sophisticated schemas, with greater individual variation. Those schemas adopted by the PRHOs (prescribing "novices") could be subsumed by, rather than contradicted by, those of the consultants (prescribing "experts"), with a transitional stage demonstrated by the SHOs. The most noticeable distinction was the greater emphasis by consultants on holistic patient care and what might be seen as their separate schemas for appropriate prescribing stemmed from that premise. In contrast, junior doctors appeared to have had a single schema that encompassed both prescribing generally and appropriate prescribing. CONCLUSIONS: Although the design of this study was cross-sectional rather than longitudinal, the findings suggest that the acquisition and adjustment of schemas and schema systems are significant factors in the professional development of the hospital doctor from novice through to expert. It could be hypothesised that house officers possess simpler schemas as a way of coping with their job demands, which evolve in complexity as they gain experience. However, the transitional stage found with the SHOs is critical during cognitive development, with implications for the training and support available to doctors throughout their professional careers.     

Should we teach using schemas? Evidence from a randomised trial

Medical Education 2012: 46: 815–822 Context Schema‐based instruction may alter knowledge organisation and diagnostic reasoning strategies through the provision of structured knowledge to novice trainees. The effects of schema‐based instruction on diagnostic accuracy and knowledge organisation have not been rigorously tested. Methods Year 2 medical students were randomised to learn four cardiac diagnoses using schema‐based instruction (n = 26) or traditional instruction (n = 27) on a high‐fidelity cardiopulmonary simulator (CPS). Students completed case‐based learning in groups of two to five and underwent individual written and practical tests. The written test consisted of questions testing features that linked or distinguished diagnoses (structured knowledge) and questions testing features of individual diagnoses (factual knowledge). A practical test of diagnostic accuracy on the CPS was performed for two diagnoses present in the learning phase (taught lesions) and two untaught lesions. A majority of students (n = 37, 70%) voluntarily returned for follow‐up written testing 2–4 weeks later. Results Learning time and accuracy did not differ between students on schema‐based and those on traditional instruction. Students receiving schema‐based instruction performed better on structured knowledge questions (p < 0.001) and no differently on factual knowledge questions (p = 0.7). Relative differences between groups remained unchanged on follow‐up testing. Diagnostic success was higher in the schema‐based instruction group for taught lesions (mean difference = 38%, 95% confidence interval [CI] 20–56; p < 0.001) and untaught lesions (mean difference = 31%, 95% CI 15–48; p < 0.001). Conclusions Schema‐based instruction was associated with improved retention of structured knowledge and diagnostic performance among novices. This study provides important proof‐of‐concept for a schema‐based approach and suggests there is substantial benefit to using this approach with novice trainees.     

Profile of cognitive problems in schizophrenia and implications for vocational functioning

Aim:  This literature review attempts to profile specific areas of cognition that have shown unique and consistent evidence of dysfunction among people with schizophrenia. In addition, their impact on vocational functioning is illustrated, so as to highlight the importance of managing these cognitive difficulties in vocational rehabilitation.
Methods:  Literature search was carried out on seven key cognitive domains identified by the National Institute of Mental Health in the USA. Their impact on vocational function was also reviewed.
Results:  It is found that attention, declarative and working memory, reasoning, problem-solving and social cognition are areas of impairment that have great impact on vocational functioning. Attention and memory problems affect learning of new work tasks. Executive function is particularly crucial in determining supported and open employment outcomes, as executive dysfunction cannot be easily compensated. Lastly, social cognition plays a major role in determining the success of workplace social exchanges.
Conclusion:  Occupational therapists need to have a good understanding of the profile of cognitive problems among people with schizophrenia, in order to tailor our intervention according to their cognitive strengths and difficulties. Several cognitive remediation strategies and programs have been designed specifically for people with mental illness. Equipping ourselves with skills in conducting such programs will augment our expertise in vocational rehabilitation.     

Piano keyboard training and the spatial–temporal development of young children attending kindergarten classes in Greece

This research had three main goals: to control whether children would show significant improvement in cognitive test scores following piano/keyboard instruction; to compare whether the spatial tasks would show greater improvement than other tasks; and to examine whether the effects of piano/keyboard training on spatial tasks are gender differentiated. Sixty‐one kindergarten children received two piano/keyboard lessons weekly during one school year. Six Kaufman Assessment Battery for Children subtests were administered before and after the instruction period. Following piano/keyboard instruction, participants improved significantly in Hand Movements, Gestalt Closure, Triangles, Spatial Memory, and Arithmetic but not in Matrix Analogies. Boys had significantly better gain scores than girls in Triangles. It is hoped that these findings contribute to the growing body of research investigating the extra‐musical effects of music instruction.     

Workplace-based assessment: raters’ performance theories and constructs

Weaknesses in the nature of rater judgments are generally considered to compromise the utility of workplace-based assessment (WBA). In order to gain insight into the underpinnings of rater behaviours, we investigated how raters form impressions of and make judgments on trainee performance. Using theoretical frameworks of social cognition and person perception, we explored raters’ implicit performance theories, use of task-specific performance schemas and the formation of person schemas during WBA. We used think-aloud procedures and verbal protocol analysis to investigate schema-based processing by experienced (N = 18) and inexperienced (N = 16) raters (supervisor-raters in general practice residency training). Qualitative data analysis was used to explore schema content and usage. We quantitatively assessed rater idiosyncrasy in the use of performance schemas and we investigated effects of rater expertise on the use of (task-specific) performance schemas. Raters used different schemas in judging trainee performance. We developed a normative performance theory comprising seventeen inter-related performance dimensions. Levels of rater idiosyncrasy were substantial and unrelated to rater expertise. Experienced raters made significantly more use of task-specific performance schemas compared to inexperienced raters, suggesting more differentiated performance schemas in experienced raters. Most raters started to develop person schemas the moment they began to observe trainee performance. The findings further our understanding of processes underpinning judgment and decision making in WBA. Raters make and justify judgments based on personal theories and performance constructs. Raters’ information processing seems to be affected by differences in rater expertise. The results of this study can help to improve rater training, the design of assessment instruments and decision making in WBA.     

Provider Training and Education in Disease Management

Disease management has emerged as an important tool to increase quality of care, improve patient outcomes and control costs. Reducing provider practice variation is a key aspect of successful disease management. Clinical practice guidelines are a useful tool to reduce practice variation but are often underutilized. Provider training interventions, particularly using multiple educational strategies, have been proven to be effective in increasing guideline adherence. For maximal effect, provider training must also be combined with system interventions to support and sustain new provider behaviors.Educational technologies encompass electronic-based delivery methods and innovations in instructional design such as adult education, problem-based learning, and competency-based training. Innovations in educational technology are lowering common barriers to provider training such as limited provider time, less provider acceptance of traditional classroom methods and limited organizational training resources. Electronic technologies are central to delivery of distance learning, which uses technology to link instructors separated from learners by time and/or distance. Distance learning includes synchronous methods (which link learners who are separated by geographic distance but allow for simultaneous interaction) and asynchronous methods (which allow for interaction at different times). The range of electronic technologies include relatively simple and inexpensive methods requiring minimal infrastructure such as audio or videotape instruction, to technology-intensive methods such as videoconferencing or telemedicine, involving substantial infrastructure. Computer-assisted learning methods range from simple freestanding programs, to more sophisticated interactive Internet-based instruction, to highly sophisticated and realistic patient simulators.Constraints to implementing innovative educational technologies include providers’ discomfort with electronic technology, increased time and cost of instructor-intensive face-to-face instructional methods and the requirement for extensive infrastructure and technical support of some electronic-based technologies. Selecting appropriate educational technology for disease management provider training requires careful consideration of both program and provider characteristics. More research is needed on the comparative effectiveness, synergies, limitations and health economics of innovative educational technologies in provider training.     

Diagnostic ability of medical students in relation to their learning characteristics and preclinical background

Is the diagnostic ability of medical students — as appraised by the Diagnostic Thinking Inventory (DTI) — influenced by the learners’ characteristics, or the way they acquired basic knowledge? This question was explored in a 4-year consecutive sampling of clinical clerkship students. DTI inventory scores (flexibility in thinking and structure in memory), learners’ characteristics (learning style, self-confidence as a learner, and motivation to learn), together with knowledge scores (grade-point average and problem-solving test) were measured and analysed for their relationships and the differences between groups. Results revealed that higher scores of the DTI measures were associated with students’ high self-confidence, high motivation to learn, and abstract learning types. Correlation coefficients showed significant relationships between the DTI scores and both knowledge measures. In addition, t-tests showed that students with an integrated teaching background and problem-based learning (PBL) experience obtained significantly higher scores for structure in memory. The findings suggest that the inventory scores are sensitive to both cognitive and non-cognitive factors. The inventory may be useful in detecting subtle influences on diagnostic ability differentiation in medical students.     

Teacher Professionalism - An Innovative Programme for Teaching Mathematics to Foundation Level Learners with Limited Language Proficiency

This article reports on results derived from a quantitative research into the language proficiency of disadvantaged preschoolers within a Griqua community near Christiana in the Free State province (South Africa) with a population of approximately one hundred and fifty families. The learners' main language is a dialect of Afrikaans, but (to a lesser extent) they also speak Xhosa and Xhoi-San (two of the indigenous African languages), as well as non-standard English at home. Preschoolers from this settlement attend a preschool where standard Afrikaans and English are spoken (double medium preschool). The aim of this project was to determine the ways that limited language proficiency impact on learners' readiness for mathematics instruction, and to define the link between limited language proficiency and non-readiness for mathematics instruction at foundation phase. The results proved a link between limited language proficiency and non-readiness for foundation level mathematics instruction due to limited thinking skills, which constitute limited cognitive academic language proficiency. The concept cognitive academic language proficiency refers to those language skills that are essential to transcend ordinary social language. On average, children need between five and seven years to attain cognitive academic language proficiency of such a level that would support grade-level performance on academic tasks. The findings were utilized to construct and propose a programme for teaching mathematics to foundation level learners with limited language proficiency.     

Decrements in cognitive performance in metal inert gas welders exposed to aluminium

OBJECTIVES: Often little has been discovered of the cognitive functions affected by occupational toxins because many functions cooperate to produce the single performance scores typically reported from neuropsychological tests. To facilitate the interpretation of neuropsychological scores, the issue of occupational exposure to aluminium was examined with an approach intended to increase understanding of those cognitive processes that may be affected. METHODS: The investigation was a cross sectional study of asymptomatic aluminium welders and a reference group of mild steel welders. Based on urinary aluminium concentrations, welders were classified into a reference (n = 28), low (n = 27), and high (n = 24) exposure group. The mean urinary aluminium concentrations were 0.46, 2.25, and 9.98 mumol/l, respectively. A comprehensive neuropsychological examination was undertaken to assess psychomotor function, simple visual reaction time, attention related tasks, verbal and visual or visuospatial abilities as well as verbal and visual learning and memory. RESULTS: Aluminium welders showed no impairment on the finger tapping, Santa Ana dexterity, simple visual reaction times, any of the verbal memory tasks, the similarities subtest of Wechsler adult intelligence scale, or the Stroop task. However, the low exposed group performed poorer on the memory for designs and on more difficult block design items demanding preliminary visuospatial analysis. The time limited synonym task, embedded figures, digit symbol speed, and the backward counting component of the divided attention task showed exposure-response relations. CONCLUSIONS: The impairments found were circumscribed. When the neuropsychological tasks were scored to show some of the underlying theoretical cognitive structures, the results indicated that performance difficulties were mainly detected in tasks requiring working memory, particularly that relating to processing of visuospatial information. There was also evidence that such impairments are more readily found in time limited tasks involving visually presented material, in which effective visual scanning combined with control of working memory is demanded.       

The Critical Role of Working Memory in Academic Achievement

Far too many culinary arts educators are unaware of the critical role that working memory plays in student’s ability to perform cognitive and academic tasks, such as reading, note taking, and studying for tests (memorization). In this article, we provide research that suggests working memory may be uniquely responsible for the difficulties faced by culinary students in the kitchen and classroom. This literature review not only defines working memory but describes its functionality based on the work of key researchers in the field and gives practical recommendations to apply this knowledge in culinary arts education. The vital role that working memory plays in teaching and learning should give teachers great pause and make them re-examine their approach to instructional design to enhance the academic achievement potential of culinary students.     

Stakes in the eye of the beholder: an international study of learners’ perceptions within programmatic assessment

Objectives

Within programmatic assessment, the ambition is to simultaneously optimise the feedback and the decision‐making function of assessment. In this approach, individual assessments are intended to be low stakes. In practice, however, learners often perceive assessments designed to be low stakes as high stakes. In this study, we explored how learners perceive assessment stakes within programmatic assessment and which factors influence these perceptions.

Methods

Twenty‐six learners were interviewed from three different countries and five different programmes, ranging from undergraduate to postgraduate medical education. The interviews explored learners’ experience with and perception of assessment stakes. An open and qualitative approach to data gathering and analyses inspired by the constructivist grounded theory approach was used to analyse the data and reveal underlying mechanisms influencing learners’ perceptions.

Results

Learners’ sense of control emerged from the analysis as key for understanding learners’ perception of assessment stakes. Several design factors of the assessment programme provided or hindered learners’ opportunities to exercise control over the assessment experience, mainly the opportunities to influence assessment outcomes, to collect evidence and to improve. Teacher–learner relationships that were characterised by learners’ autonomy and in which learners feel safe were important for learners’ believed ability to exercise control and to use assessment to support their learning.

Conclusions

Knowledge of the factors that influence the perception of assessment stakes can help design effective assessment programmes in which assessment supports learning. Learners’ opportunities for agency, a supportive programme structure and the role of the teacher are particularly powerful mechanisms to stimulate the learning value of programmatic assessment.     

Foundations of problem-based learning: some explanatory notes

Summary. The present article elaborates on cognitive effects of problem-based learning put forward by Schmidt, De Volder, De Grave, Moust & Patel (1989) and Norman & Schmidt (1992) . Its purpose is to discuss, in some detail, the theoretical premises of this approach to learning and instruction. It is argued that problem-based learning, above all, promotes the activation of prior knowledge and its elaboration. Evidence is reviewed demonstrating that these processes actually occur in small-group tutorials and that the processing of new information is indeed facilitated by discussion of a relevant problem. These effects must be attributed to a reorganization taking place in the knowledge structures of students as a result of problem-oriented study. In addition, a cognitive process called epistemic curiosity (or intrinsic interest) is enabled. Some directions for further research are outlined. The contribution starts, however, with a discussion of the philosophical and pedagogical roots of problem-based learning.     

Visual imagery imitation skills and cognitive functions in patients with Schizophrenia

Background/ObjectivesVisual demonstration by occupational therapists is very common in psychiatric treatment, however, some patients with schizophrenia could not imitate the actions despite the absence of any physical impairments. Therefore, the purpose of this study was to identify how cognitive functions such as attention and cognitive processes in the imitation process is necessary and how these processes were related to the ability to convert this into action (imitation) in patients with schizophrenia.MethodThe participants were patients with schizophrenia with mean age 59.2 (± 11.3) years, 23 were men and 10 were women. The participants were tested for imitation ability and cognitive function, working memory, and motor imagery.ResultsThree subjects achieved full scores in the visual imitation test. However, the median of the total score was 10.0, with many subjects failing to imitate multiple tasks. Imitation learning is associated with duration of illness(t = −4.09, p = .000), mental health(t = −2.30, p = .029), and cognitive function such as the ability to retain visual information(t = −2.97, p = .006), and that these factors are interrelated.ConclusionTo effectively promote imitation learning in patients with schizophrenia, occupational therapists need to establish teaching methods that make it easier for learners to retain visual information from the early stages of their illness.     

Mental model progression in learning the electron transport chain: effects of instructional strategies and cognitive flexibility

This study investigated the effect of two instructional strategies, segmented and holistic, on the progression over time of learners’ mental models toward that of an expert with the moderator of cognitive flexibility. Sixty-four juniors and seniors in a college metabolism course were randomly assigned to one of the two strategies for instruction on the electron transport chain. The data were analyzed with a repeated measures general linear model. Mental models progressed significantly for both strategies (p < .001), and a significant interaction was found between cognitive flexibility and instructional strategy on mental model progression (p = .02). The segmented strategy was superior for learners with higher cognitive flexibility but inferior to the holistic strategy for lower cognitive flexibility learners. Results have important implications for differentiating instruction on the basis of learner characteristics.