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关键词： Computer science education   Computational thinking   Programming   Systematic review   K-12  

摘要： This systematic review examined how computer science (CS) education was implemented in schools and its efficacy for developing students' computational thinking (CT). Sixty-six papers were selected for this systematic review and analyzed for patterns in relation to the implementation of CS education in K-12 schools and its impact on the development of students' CT skills. Although educational interventions have not always been successful in CS education, this review provides strong evidence that overall, CS education promotes the development of students' CT in the K-12 setting while improving their creative and critical thinking skills. We recommend early access to CS education, various innovative instructional approaches to CS education and appropriate support and guidance for student learning.

关键词： capital punishment   clothing   executions   gender   resistance   subversion  

摘要： In this paper we examine the dress of execution victims. Executions provide both the convict and the state with an opportunity to claim honor and respectability. Drawing on newspaper accounts of executions conducted between 1840 and 1940, we demonstrate that convict attire reveals an important tension between the convicts' gendered character claims and the efforts by execution managers to arrange a credible execution. But whereas displays of masculinity reinforce more than challenge the propriety of executions, women's femininity displays challenge not only the propriety of executions, but also the respectability of those tasked with their killing. We conclude that the subversive potential of clothing is found not only in the garments themselves, nor only on the wearers' intentions, but also on the institutional settings in which they are presented.

关键词： Computer science   Online teaching and learning   Instructional strategies   Assessment   Design   Facilitation  

摘要： Current research surrounding online computer science education emphasizes the need for high-quality professional development opportunities. However, there is a gap in research in the inclusion of online computer science educators to identify needs and strategies that make the online computer science courses effective. Through a Research-to-Practice Partnership (RPP), this paper examines the instructional strategies and recommendations from online Computer Science teachers. This study seeks to better understand (1) What design, facilitation, and assessment strategies do teachers use to teach programming online? and (2) What recommendations do teachers have for those interested in teaching programming online? The feedback teachers provided during the study assisted in identifying the current needs in online AP Computer Science. The participants suggested additional ways the RPP could support teachers in strengthening their practice, which has assisted in the production of high-quality professional development to support novice teachers entering the field of Computer Science.

关键词： Computer science education   Culturally responsive computing   Research-practice partnership   Elementary education  

摘要： Implementing computer science education in an elementary classroom is at the forefront of computing education. Nevertheless, the literature on K-12 Computer Science (CS) education offers limited guidance for developing elementary CS curricula that lead to multiple career paths through project-based learning. Particularly, more research is needed on culturally responsive elementary school computing that leverages students' cultural references to create a more equitable CS education that acknowledges one's identity, culture, or background in the curriculum planning. This paper offers an approach for designing culturally responsive computing for upper elementary students from a highly diverse, low socio-economic school district using a research-practice approach. The approach can be adapted for other schools that face unique diversity and curricular challenges.

关键词： Early childhood education   Preservice teachers   Computer science   Coding   Gender stereotypes  

摘要： The purpose of this exploratory study was to investigate early childhood preservice teachers' perceptions of computer science and gender stereotypes in computer science, and perceptions of coding in early childhood education. Quantitative and qualitative data were collected from early childhood preservice teachers enrolled in a teaching methods course at a large southeastern university in the U.S. Findings showed that participants had misconceptions about what CS is and what computer scientists do. They were also neutral about coding and its integration in early childhood education. Both qualitative and quantitative data supported that the participants did not hold gender stereotypes in CS.

关键词： Learning systems   Neural networks   Computer science   Feature extraction   Zinc   Cybernetics   Gallium nitride   Broad learning system (BLS)   classification   incremental learning   weighted generalized cross-validation (WGCV)  

摘要： The broad learning system (BLS) is an emerging flat network, which has demonstrated its outstanding performance in classification and regression problems. The regularization plays an important role in the performance of the BLS. In real applications, since the BLS network is usually expanded dynamically, a predetermined regularization parameter may reduce the performance of the network. Using a fixed regularization in some cases, the classification accuracy of the BLS decreases dramatically when we expand the network. To alleviate this problem, we propose a method that automatically finds appropriate regularization parameters for different datasets, which is based on the weighted generalized cross-validation (WGCV). The experimental results indicate that the WGCV method improves the performance of the BLS, and alleviates the accuracy decrease of the incremental learning algorithm.

关键词： Encryption   Databases   Computer science   Faces   Two dimensional displays   Encrypted database   data privacy   order-preserving encryption   order-revealing encryption  

摘要： Order-preserving encryption (OPE) is a cryptographic primitive that preserves the order of plaintexts. In the past few years, many OPE schemes were proposed to solve the problem of executing range queries in encrypted databases. However, OPE leaks some certain information (for example, the order of ciphertext), so it is vulnerable to many attacks. Subsequently, order-revealing encryption (ORE) was proposed by Boneh et al. (Eurocrypt 2015) as a generalization of order-preserving encryption. It breaks through the limitation of the numeric order of OPE plaintext. It implements ciphertext comparison for any specific form of plaintext through a publicly computable comparison function. In this article, we aim to design a new ORE scheme which reduces the leakages and preserves the practicality in terms of ciphertext length and encryption time. We first propose the hybrid model named HybridORE. Then, we propose an improved scheme named EncodeORE which achieves acceptable security and appropriate ciphertext length. They both explore the encode strategy of encoding plaintext into different parts and apply suitable ORE algorithms to each part according to its security characteristics to reduce leakages. Compared with the typical CLWW scheme (FSE 2016) and Lewi-Wu (CCS 2016) in large domain, they have fewer leakages. The experiment shows that the proposed EncodeORE is very practical.

关键词： Communities of practice   Computational thinking   Computer science   Cooperative/collaborative learning   Distance education and online learning   Teacher professional development   Teaching/learning strategies  

摘要： The COVID-19 pandemic led to an urgent need for professional development (PD) experiences to support teacher learning across hybrid and digital contexts. This study investigates teachers' experiences in a Virtual Pivot, a PD workshop designed to support computational thinking integration into disciplinary teaching. Participants were 151 middle and high school content area teachers, including 49 teachers who participated in previous face-to-face workshops. Virtual Pivot employed research-based design principles for virtual teacher PD, including asynchronous and synchronous engagement, explicit instruction in technological tools and scaffolds for teacher collaboration. Data sources included pre-PD surveys (n = 151), post-PD surveys (n =119), interviews (n = 57) and six-month follow-up surveys (n = 105). Findings describe elements of Virtual Pivot which supported teacher learning and engagement (virtual community of practice, PD structure, during-PD support, pre-PD support and badges). We conclude by discussing this study's theoretical, methodological and practical contributions for designing and investigating virtual computational thinking PD experiences.

关键词： Smart contracts   Blockchain   Semantics   Cryptography   Fuzzing   Computer science   Solid modeling   Smart contract   test oracle   security vulnerability   fuzzing  

摘要： Despite the high stakes involved in smart contracts, they are often developed in an undisciplined manner, leaving the security and reliability of blockchain transactions at risk. In this article, we introduce ContraMaster-an oracle-supported dynamic exploit generation framework for smart contracts. Existing approaches mutate only single transactions;ContraMaster exceeds these by mutating the transaction sequences. ContraMaster uses data-flow, control-flow, and the dynamic contract state to guide its mutations. It then monitors the executions of target contract programs, and validates the results against a general-purpose semantic test oracle to discover vulnerabilities. Being a dynamic technique, it guarantees that each discovered vulnerability is a violation of the test oracle and is able to generate the attack script to exploit this vulnerability. In contrast to rule-based approaches, ContraMaster has not shown any false positives, and it easily generalizes to unknown types of vulnerabilities (e.g., logic errors). We evaluate ContraMaster on 218 vulnerable smart contracts. The experimental results confirm its practical applicability and advantages over the state-of-the-art techniques, and also reveal three new types of attacks.