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Augmented reality (AR) has the potential to create compelling learning experiences. However, there are few research works exploring the design and evaluation of AR for educational settings. In our research, we treat AR as a type of multimedia that is situated in authentic environments and apply multimedia learning theory as a framework for developing our educational applications. We share our experiences in developing a handheld AR system and one specific use case, namely, situated vocabulary learning. Results of our evaluations show that we are able to create AR applications with good system usability. More importantly, our preliminary evaluations show that AR may lead to better retention of words and improve student attention and satisfaction.

Usability evaluations are important to improving handheld augmented reality (HAR) systems. However, no standard questionnaire considers perceptual and ergonomic issues found in HAR. The authors performed a systematic literature review to enumerate these issues. Based on these issues, they created a HAR usability scale that consists of comprehensibility and manipulability scales. These scales measure general system usability, ease of understanding the information presented, and ease of handling the device. The questionnaires' validity and reliability were evaluated in four experiments, and the results show that the questionnaires consistently correlate with other subjective and objective measures of usability. The questionnaires also have good reliability based on the Cronbach's alpha. Researchers and professionals can directly use these questionnaires to evaluate their own HAR applications or modify them with the insights presented in this article.

Figure 1: We created a usability scale for evaluating handheld augmented reality (HAR) applications. We defined our usability scale based on perceptual and ergonomic issues encountered by users, and then assessed it using three experiments representative of common HAR tasks. AbstractHandheld augmented reality (HAR) applications must be carefully designed and improved based on user feedback to sustain commercial use. However, no standard questionnaire considers perceptual and ergonomic issues found in HAR. We address this issue by creating a HAR Usability Scale (HARUS).To create HARUS, we performed a systematic literature review to enumerate user-reported issues in HAR applications. Based on these issues, we created a questionnaire measuring manipulability -the ease of handling the HAR system, and comprehensibilitythe ease of understanding the information presented by HAR. We then provide evidences of validity and reliability of the HARUS questionnaire by applying it to three experiments. The results show that HARUS consistently correlates with other subjective and objective measures of usability, thereby supporting its concurrent validity. Moreover, HARUS obtained a good Cronbach's alpha in all three experiments, thereby demonstrating internally consistency.HARUS, as well as its decomposition into individual manipulability and comprehensibility scores, are evaluation tools that researchers and professionals can use to analyze their HAR applications. By providing such a tool, they can gain quality feedback from users to improve their HAR applications towards commercial success.

Virtual objects can be visualized inside real objects using augmented reality (AR). This visualization is called AR X-ray because it gives the impression of seeing through the real object. In standard AR, virtual information is overlaid on top of the real world. To position a virtual object inside an object, AR X-ray requires partially occluding the virtual object with visually important regions of the real object. In effect, the virtual object becomes less legible compared to when it is completely unoccluded. Legibility is an important consideration for various applications of AR X-ray. In this research, we explored legibility in two implementations of AR X-ray, namely, edge-based and saliency-based. In our first experiment, we explored on the tolerable amounts of occlusion to comfortably distinguish small virtual objects. In our second experiment, we compared edge-based and saliency-based AR X-ray methods when visualizing virtual objects inside various real objects. Moreover, we benchmarked the legibility of these two methods against alpha blending. From our experiments, we observed that users have varied preferences for proper amounts of occlusion cues for both methods. The partial occlusions generated by the edgebased and saliency-based methods need to be adjusted depending on the lighting condition and the texture complexity of the occluding object. In most cases, users identify objects faster with saliency-based AR X-ray than with edge-based AR X-ray. Insights from this research can be directly applied to the development of AR X-ray applications.

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Engineers and educators alike have prototyped a variety of augmented reality learning experiences (ARLEs). However, adapting ARLEs in educational practice would require an interdisciplinary approach that considers learning theory, pedagogy and instructional design. To address this requirement, we model ARLEs as learning objects by outlining the necessary components, and we propose a participatory design to demonstrate the authoring process of an augmented reality learning object (ARLO). ARLOs can be made useful in many scenarios if teachers are empowered to edit its context elements, content and instructional activity. Lastly, we point to the research questions entailed in modeling ARLEs as ARLOs.

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