Kuo-En Chang

How many heads are better than one? The reliability and validity of teenagers' self- and peer assessments

Self- and peer assessments are becoming more popular in classrooms, but there are few data on the reliability and validity of such assessments performed by school children. Because these factors are greatly affected by the number of raters, we conducted two studies to determine the rating behaviours of teenagers in self- and peer assessments, and how the number of raters influences the reliability and validity of self- and peer assessments. The first study involved 116 seventh graders (the first grade of middle school), where students individually playing musical recorders were subject to self- and peer assessments. The second study involved 110 eighth graders, with Web pages constructed by students being subject to self- and peer assessments. Generalizability theory and criterion-related validity were used to obtain the reliability and validity coefficients of the self- and peer ratings. Analyses of variance were used to compare differences in self- and peer ratings between low- and high-achieving students. The coefficients of reliability and validity increased with the number of raters in both studies, reaching the acceptable levels of 0.80 and 0.70, respectively, with 3 or 4 raters in the first study (involving assessments of individual performance) and with 14-17 raters in the second study (involving assessments of group work). Furthermore, low- and high-achieving students tended to over- and underestimate the quality of their work in self-assessment, respectively. The discrepancy between the ratings of students and experts was higher in group-work assessments then in individual-work assessments. The results have both theoretical and practical implications for researchers and teachers.

Supporting teachers' reflection and learning through structured digital teaching portfolios

Digital teaching portfolios have been proposed as an effective tool for teacher learning and professional development, but there is a lack of empirical evidence supporting their effectiveness. This study proposed the design of a structured digital portfolio equipped with multiple aids (e.g. self-assessment, peer assessment, discussion and journal writing) for the professional development of teachers. This study also empirically evaluated the reflection and professional development as demonstrated in digital teaching portfolios with multiple supporting measures. Fourty-four in-service substitute teachers participated in a course of classroom assessment and used a web-based portfolio system. Based on the framework of teacher reflective thinking developed by Sparks-Langer et al., we found that most teachers demonstrated moderate levels of reflection in their journals but only one-third of them showed the highest level of reflection. We also found that the professional knowledge of teachers about classroom assessment - as shown by their implementation of it - improved significantly during the construction of portfolios. The above findings also represent good evidence that digital portfolios with multiple aids are beneficial to teacher reflection and professional development.

A programming learning system for beginners-a completion strategy approach

The purpose of this research is to develop a programming learning system for beginners using the completion strategy. The completion strategy uses well-designed programs to let students engage in completing, modifying, and extending their programs. The completion strategy is a paradigm of learning by examples with learning enforcement. In this paper, learning theories of the completion strategy are investigated. A template technique is employed to realize the strategy. An educational experiment was made to show the learning impact of the proposed system. The experimental result shows that the completion strategy is benefit to the programming learning for beginners.

Constrained via minimization with practical considerations for multi-layer VLSI/PCB routing problems

The constrained via minimization problem in a multi-layer VLSflCB routing environment is the problem of determining which layers can be used for routin the wire segments in the interconnections of nets such that t t e number of vias is rmnimized. In this aper, a Segment-Crossing Graph model is introduced, then ageuristic algorithm is pro osed on the basis of this gra h model. The algonthrn is divldexinto two ste s: GLOBAL h&NIMIZATlON and LOCAL MINIMIZATI&. In addition, practical considerations, such as restricted terminals and adjacent limitation, are addressed in this paper. Finally, the algorithm is evaluated by some famous routin examples usin five layers. The results show that 45 percent 05 vias minime% are obtained on an average. In& Tern via minimization, layer assignment, VLSUPCB routing, NP-complete.

Neural-fuzzy classification for segmentation of remotely sensed images

An unsupervised classification technique conceptualized in terms of neural and fuzzy disciplines for the segmentation of remotely sensed images is presented. The process consists of three major steps: 1) pattern transformation; 2) neural classification; 3) fuzzy grouping. In the first step, the multispectral patterns of image pixels are transformed into what we call coarse patterns. In the second step, a delicate classification of pixels is attained by applying an ART neural classifier to the transformed pixel patterns. Since the resultant clusters of pixels are usually too keen to be of practical significance, in the third step, a fuzzy clustering algorithm is invoked to integrate pixel clusters. A function for measuring clustering validity is defined with which the optimal number of classes can be automatically determined by the clustering algorithm. The proposed technique is applied to both synthetic and real images. High classification rates have been achieved for synthetic images. We also feel comfortable with the results of the real images because their spectral variances are even smaller than the spectral variances of the synthetic images examined.

Via minimization with associated constraints in three-layer routing problem

Via minimization is the same as the layer assignment problem in VLSI or PCB routing. It consists of determining which layers can be used for routing the wire segments such that the number of vias can be minimized. A heuristic algorithm is presented to globally eliminate the vias in the three-layer channel routing. Some associated constraints, such as restricted terminals and adjacent limitation, are addressed extensively. According to the results, the algorithm is fast and efficient, thus generating very good results.<<ETX>>

Web/spl I.bar/Soc: a Socratic-dialectic-based collaborative tutoring system on the World Wide Web

A Web/spl I.bar/Soc tutoring system for recursion concept learning is proposed. The system integrates different modes of learning, synchronous and asynchronous, collaborative and individualized, into a World Wide Web (WWW) environment. The paper proposes a collaborative learning protocol. Based on the protocol, the principles of the Socratic dialogue are applied to the collaborative learning of recursion concepts. In order to evaluate the effects on learning of the Web/spl I.bar/Soc system, an educational experiment was conducted. The results show that the effects from the Web/spl I.bar/Soc system were more obvious than merely studying articles.

Socratic-dialectic learning system of recursion programming

The purpose of this research was to construct a recursion programming learning system based on Socratic dialogue. Since recursion programming learning relates to the formation and evolution of mental models, the learning may not be effective if teachers rely only on simply telling the students the standard solutions. Instead, teachers should urge the students to consider the mistakes and contradictions discovered by themselves in the learning process. Socratic dialogue is applied as a dialectic method, which presents questions to students and encourages them to reflect on their own thinking. In this study, we explored the fundamental Socratic dialogue reasoning principles and implemented these principles through production rules. This Socratic-dialectic learning system was implemented using database techniques and evaluated by an empirical study. According to the experimental results, the Socratic dialogue was proven to have positive impact on recursion programming learning.

A Programming Learning System for Beginners - A Completion Strategy Approach

The purpose of this research is to develop a programming learning system using the completion strategy for beginners. The completion strategy was proved to have feasible result for beginners. Based on the previous works, most of programming tutors require students to write programs and then to evaluate and explain the program correctness. This “program generation” approach is not suitable to beginners. Therefore, the purpose of this research adopts the completion strategy to have beginners learn programming. The completion strategy is to utilize the well-designed programs to let students engage in completing, modifying, and extending their program. This research first investigates the programming learning theories; then initiates the system structure of the programming learning system. Template technique is used to implement the proposed system.

Efficient algorithms of wiring channels with movable terminals

The problem of wiring a channel of movable terminals in a VLSI chip is presented. Two subproblems are addressed: maximum alignment and wireable placement. Maximum alignment is to reassign terminal positions in the channel in order to maximize the number of nets that can be implemented as straight connections. Wireable placement is to find an assignment of the movable terminals to the vertical tracks in the channel that eliminates the vertical conflicts between nets. A restriction is imposed on the number of unconnected terminals in the maximum alignment problem to ensure that the number of columns in the channel is not increased in the process. The two subproblems are solved using two heuristic algorithms. Some well-known examples, including Deutschs difficult example, are used as test cases. The results show that both channel width and via usage are reduced significantly by using the procedures. >