Blindfolded sighted, adventitiously blind, and congenitally blind subjects performed a set of navigation tasks. The more complex tasks involved spatial inference and included retracing a multisegment route in reverse, returning directly to an origin after being led over linear segments, and pointing to targets after locomotion. As a group, subjects responded systematically to route manipulations in the complex tasks, but performance was poor. Patterns of error and response latency are informative about the internal repredentation used; in particular, they do not support the hypothesis that only a representation of the origin of locomotion is maintained. The slight performance differences between groups varying in visual experience were neither large nor consistent across tasks. Results provide little indication that spatial competence strongly depends on prior visual experience.Effective navigation by humans involves a number of skills, including updating one's position and orientation during travel, forming and making use of representations of the environment through which travel takes place, and planning routes subject to various constraints (shortest distance, minimal travel time, maximum safety, etc.); see Rieser, Guth, and Hill (1982);Strelow (1985). Methods of updating position and orientation can be classified according to the type of information used: position, velocity, or acceleration. Position-based navigation (called pilotage or piloting) relies on external signals indicating the observer's position and orientation (Baker, 1981;Etienne, 1992); such signals would include visible or audible landmarks known to the traveler or those from electronic navigation aids. Velocity-

Literacy for a 21st century context is far more complex than reading and writing print. As society and information and communication technology (ICT) has changed, so what counts as literacy and how a person is deemed to be literate has changed. Students from lowsocio-economic backgrounds in the later years of schooling require access to multiple literacies mediated through ICT and to teachers who are willing to provide opportunities for them to be taught explicitly. ICT can promote the learning of the content as well as learning the literacies associated with specific subject areas. This paper will focus on how three teachers in the later years of schooling (years 9-12) used technology to enhance learning and engagement of students in learning the literacies associated with their subject. They challenged the hegemony of print literacy by providing opportunities to develop students understanding, critique and creation of multimodal texts, but also supported students in achieving more effective print literacy. These teachers provided appropriate teaching for students from low socio-economicbackgrounds, engaging them in thinking, feeling and acting at high levels while simultaneously providing positive messages about their knowledge, ability, control, place and voice. Their pedagogical approach supported the development of cultural and social capital that will enhance their students' life options.

The ability of sighted, blindfolded individuals to navigate while walking was assessed in two types of tasks, one requiring knowledge of a route that previously had been navigated and another requiring more complex spatial inference or computation. A computerized measurement system monitored spatial position. The route tasks included maintenance of a heading, distance and turn reproduction and estimation, and turn production. The inferential task required completion of a multisegment pathway by returning directly to the origin. pathways were replicated at two different scales. Measures for the route-knowledge tasks indicated a substantial ability to navigate in the absence of visual cues. Route reproduction performance was particularly accurate despite intrinsic veering tendencies. A substantial increase in error was observed in the pattern-completion task. Errors in pathway completion increased with pathway complexity and were quite similar in the two scales. Correlational data suggested that performance on different route-knowledge tasks reflected differing underlying representations. The completion task led to a high correlation between absolute turn and distance error but had minimal correlations with the route tasks. The data suggest that a survey representation with some degree of scale independence was constructed for use in the pathway completion task.

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Basic addition facts performance of learning-disabled (LD) children was assessed prior to and following a period of extended practice in fact production. Consistent with current theoretical discussions (e.g., Siegler, 1987), effects of the extended practice were assessed through an examination of changes in (a) problem latencies, (b) mixed strategy usage, and (c) slope parameters of the regression function relating individual problem latencies to the size of the minimum addend. For the sample as a whole, there were reductions in response latency and in the slope of the regression function following practice. However, there were actually four discriminable groups in the sample, each slower in fact production than same-age normally achieving children but differing in their strategy usage patterns. Accordingly, differential effects of practice were expected for each group; the patterns of changes in latency, mixed strategy usage, and slope parameters were consistent with these predictions. Comparisons are made to extant data on normally achieving children. The data generally support the conclusion that the performance of most of these LD children is developmentally delayed (rather than developmentally different) relative to that of normally achieving children. The results are discussed from the perspective of optimizing instructional time through sensitive assessment of entry level skills and prediction of likely changedbenefits, given these skill levels and other incoming student characteristics. The implications for strategy identification of both differences within individuals and differences between individuals are considered, as are theoretical and methodological issues.Learning-disabled (LD) youngsters are substantially less proficient than their nondisabled peers in computing the basic number facts of addition, Requests for reprints should be sent to

Background Concept inventories (CIs) are commonly used in engineering disciplines to assess students' conceptual understanding and to evaluate instruction, but educators often use CIs without sufficient evidence that a structured approach has been applied to validate inferences about student thinking. Purpose We propose an analytic framework for evaluating the validity arguments of CIs. We focus on three types of claims: that CI scores enable one to infer (1) students' overall understanding of all concepts identified in the CI, (2) students' understanding of specific concepts, and (3) students' propensity for misconceptions or common errors. Method We applied our analytic framework to three CIs: the Concept Assessment Tool for Statics (CATS), the Statistics Concept Inventory (SCI), and the Dynamics Concept Inventory (DCI). Results Using our analytic framework, we found varying degrees of support for each type of claim. CATS and DCI analyses indicated that the CIs could reliably measure students' overall understanding of all concepts identified in the CI, whereas SCI analyses provided limited evidence for this claim. Analyses revealed that the CATS could accurately measure students' understanding of specific concepts; analyses for the other two CIs did not support this claim. None of the CI analyses provided evidence that the instruments could reliably measure students' misconceptions and common errors. Conclusions Our analytic framework provides a structure for evaluating CI validity. Engineering educators can apply this framework to evaluate aspects of CI validity and make more warranted uses and interpretations of CI outcome scores.

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