This research-to-practice full paper describes a study that employs the CTProgER educational process [37] within High School environments to enhance programming skills. Computational Thinking (CT) is recognized as crucial for developing these skills, especially in high school programming education. Teaching programming presents challenges, necessitating improved educational processes and guidelines. Based on the Anthropological Theory of Didactics, CTProgER operates on the principle that human-created entities are interconnected with individuals, forming relationships denoted as R(X,O). This research investigates the efficacy of CTProgER through a rigorous intervention study conducted in a Brazilian Technical and Vocational High School (TV High School). The results reveal a significant performance disparity between the experimental and control groups, with the experimental group showing notable improvements. These findings highlight the potential of CTProgER to guide and enhance programming instruction within high school curricula, offering valuable insights for validating educational processes.

This Research-to-Practice Full Paper aims to introduce a methodological framework to foster Computational Thinking (CT) skills by teaching programming with Educational Robotics (ER) in High School. Problem-solving is an essential skill for human development, so it is necessary to introduce actions to improve this skill in High School. It is possible to stimulate problem- solving through computer programming teaching with ER. However, as far as we know, there are no methodologies for teaching programming with ER focusing on CT development in High School that went through scientific validation of the proposal. This study is an Educational Design Research that aims to introduce a methodological framework for teaching programming in High School with ER (named CTProgER) and validate two instances of the framework. It was considered consolidated teaching methodologies with ER, combined with the Anthropological Theory of Didactics and evidence from our ER studies. As a result, we present the CTProgER Framework guideline, two instances of the CTProgER Framework, and these instances’ validation through the Delphi method.

Educational Robotics (ER) is a tool that can favor teamwork, stimulate creativity, and the ability to solve students' problems through the process of assembling and programming robots. In this sense, ER has been used to improve educational practices. There are several initiatives that seek to stimulate Computational Thinking (CT) to stand out. Although ER being used to develop CT, there are still no guidelines based on scientific studies that support this use. The objective of this Research Full Paper is to identify: a) the main pedagogical approaches are applied in classes with ER focused on developing students' CT; b) the central difficulties are encountered in classes with ER focused on developing students' CT; c) the CT skills are presents in classes with ER focused on developing students' CT; d) the instruments are used to assess students' CT during classes with ER; e) the students' profile who participated in classes with ER focused o on developing students' CT; f) the educational robotics technologies are adopted in classes focused on developing students' CT. To achieve these goals, we planned and carried out systematic mapping of the literature. The results show that, through ER, CT is approached through the teaching of programming languages in a collaborative way in Early Childhood and High School. The most CT skills observed are related to programming, such as sequencing, algorithm, loop, generalization, decomposition, and debugging. The main instruments for assessing students are tests, and the most significant difficulty is the limitation of class hours. Finally, LEGO® is the most used technology in class.

This research full paper presents the design of an automatic classifier for Computational Thinking skills in math questions, based on Machine Learning and Natural Language Processing techniques. We trained and evaluated our model using a dataset of real-world math questions. We obtained encouraging results that indicate the proposed approach may ease the process of assessing the level of alignment between math questions and Computational Thinking skills, which may help improve the problem-solving ability in students of elementary school. These results stimulate the use of automated environments for the elaboration, classification, and resolution of math questions in conformity with Computational Thinking skills.

This Research to Practice Full Paper investigates the effect of Computational Thinking (CT) and robotics on learning mathematics. CT involves problem-solving skills based on Computer Science concepts. However, there is no CT formal definition as well as information on how to integrate it with other high school subjects. Studies are still searching for methods, tools, and instruments to evaluate CT skills to allow effective adoption. Problem-solving is critical to mathematics, and introducing robotics in this context can favor the learning process. The goal of this study is to apply educational robotics in a Brazilian public high school and evaluate the impact on the development of CT skills and mathematical performance. Two research questions guide the study: (RQ1) Can the use of robotics favor the development of CT skills? (RQ2) Can the use of robotics favor math learning? The development of CT skills was evaluated through the Bebras Challenge, and the annual performance obtained by the students in mathematics was considered to evaluate the impact on mathematics. The overall results pointed out that the use of robotics can favor the learning of mathematics and they bring some indications that the use of robot kits can stimulate the development of CT skills, but still more research is needed.

Educational Robotics (ER) has revealed several benefits in the educational context, not only helping the teaching of disciplines, but also making possible the development of several abilities, such as teamwork, problem-solving, and creativity. Among various robotics kits, LEGO®Robotics has been shown one of the best results considering some evaluated criteria (modularity level, hardware, curriculum, price, etc.). Some studies analyze the teaching practices, some compare technologies, and others evaluate the kits in a pedagogical way. However, it is essential to investigate all these contexts together in order to improve the impact produced by the ER in education and to know the best teaching practices associated with the most powerful technologies. The objective of this Research Full Paper is to identify: a) environments and programming languages adopted in the LEGO®Robotics context, b) educational practices applied during classes based on LEGO®Robotics, and c) the educational levels in which robotics has been applied with positive results. To achieve these goals, we planned and carried out a systematic review of the literature. Our main findings are: a) the most widely used environment and programming language are LabVIEW along with the LEGO®'s block-based programming language, b) we identified LEGO®Robotics is used for teaching programming, interdisciplinary contents, participation in tournaments, robotics, and computational thinking, c) LEGO®Robotics is used with success by students of different levels, such as K12, undergraduate, and graduated. Finally, we discuss some problems and limitations related to ER and point out that there is no standardization of teaching practices or methodologies for evaluating results, indicating that more research is needed to find the best scenario regarding technologies, methods, and target audience.

In this paper, we analyzed whether the ability of students to solve problems can be influenced by the implementation of Computational Thinking (CT) in the teaching of mathematics. In this sense, we performed a quasi-experiment with students in the Brazilian's Basic Education Regular System (particularly in a group of students around fifteen years old) comparing their performance after being trained with practical activities using exercises in more or less conformity with well known CT concepts and capabilities. Considering the quantitative results obtained, the experimental group outperformed the control group, which worked with exercises in more and less conformity with CT, respectively. The results were statistically significant, suggesting that bringing together CT and mathematics through proper adjustments of classroom practices can have a positive influence on students abilities of solving problems. In order to strengthen this conclusion we also performed a qualitative analysis comprising students and the teacher involved in the quasi-experiment that reinforced our quantitative results.

Some researchers consider that the benefits of Computational Thinking (CT) in education are unclear, and therefore a quantitative study to understand the effects of CT skills in the basic levels of formal education is needed. The present study aims to analyze the effects of CT on the academic performance of students in high school. We seek to answer the following research questions: (RQ1) Can CT increase the problem-solving skills of students in high school? (RQ2) Is CT related to the performance of students in high school? (RQ3) Can CT improve the performance of students in high school? We conducted an analysis between two groups of students with similar profiles belonging to the same population, where the factor CT proficiency is the only feature that distinguishes both groups. The results show that there is a moderate correlation between the performance of evaluated students and their skills of CT developed by computer programming. In addition, we found that students proficient in computer programming have superior performance up to 10.2% in ENEM (National Exam of High School) assessment compared to those with little or no experience level and even better performance 21% in the WASI test problem-solving in students on attending high school.

There are various methods to evaluate the performance of file systems through the replay of file system traces. Despite this diversity, little attention was given on comparing the alternatives, thus bringing some skepticism about the results attained using these methods. In this paper, to fill this understanding gap, we analyze two popular trace replay methods through the lens of metrology. This case study indicates that the evaluated methods provide similar, good precision but are biased in some scenarios. Our results identified limitations in the implementation of the replay tool as well as flaws in the established practices to experiment with trace replayers as the root causes of the measurement bias. After improving the implementation of the trace replayer and discarding inappropriate experimental practices, we were able to reduce the bias, leading to lower measurement uncertainty. Finally, our case study also shows that, in some cases, collecting only the file system activity is not enough to accurately replay the traces; in these cases, collecting resource consumption information, such as the amount of allocated memory, can improve the quality of trace replay methods.

Despite the popularity of trace-based file system performance evaluation, there is currently no accepted methodology to capture and accurately replay file system traces. The less we know about the limitations of trace-based methodologies, the less we can rely on the obtained results. In this paper, we present a case study analyzing the two most popular trace capture methods. The results of the case study indicate that the two evaluated methods provide good precision, but significant bias in some cases. In addition to providing guidelines on how to improve the quality of trace capture, our results allow us to draw important observations about current practice. We show that bias can be corrected by the execution of a calibration procedure, a practice that is mostly absent in the methodology used in the area. Our results also revealed that, to achieve correct calibration, it is crucial to collect information about the background activity and about the operating system layer running in the experimental environment. Finally, our results allow to quantify the overall trace capture uncertainty, providing means for researches to decide on the suitability of trace capture tools for their purposes.

Current trace replay methods for file system evaluation fail to represent traced workloads accurately. When using a misrepresented workload one may take wrong conclusions about the system evaluation. For example, a system designer can miss performance problems if the replay of a trace produces an under loaded representation of the real workload. Even worse, one can take wrong design decisions, leading to optimization of untypical workloads. In this study, we captured and replayed traces from standard file systems using methods proposed in the literature, to exemplify the inaccuracy of state-of-art trace replay methods. We also exposed a shortcoming of current methodologies, in a replay of a general purpose workload trace, we observed a difference of up to 100% on request response time, caused by the choice of trace replay method.

Consensus services have been recognized as fundamental building blocks for fault-tolerant distributed systems. Many different protocols to implement such a service have been proposed, however, not a lot of effort has been placed in evaluating their performance. In particular, in the context of round-based consensus protocols for asynchronous systems augmented with failure detectors, there has been some work on evaluating how the QoS of the failure detector impacts the performance of the protocols, as well as on the trade-off between having faster decentralized decision at the expenses of generating more network load. These studies, however, focus on protocols that have no mechanism to deal with an eventual bad QoS provided by the failure detector, and have a decision pattern that is either completely centralized - only one process being able to autonomously decide - or completely decentralized - all processes being able to autonomously decide. This paper reports a thorough evaluation of the performance of a consensus protocol that has two unique features. Firstly, it mitigates the problems due to bad QoS delivered by the failure detector by allowing processes to simultaneously participate in multiple rounds. Secondly, it allows its decision pattern to be configured to have different numbers of processors allowed to autonomously decide. We have measured the decision latency of the protocol to conduct the performance analysis. The results, obtained by means of simulation, highlight the advantages and limitations of the two mechanisms and allow one to understand in a comprehensive framework how the protocol's parameters should be set, such that the best performance is achieved depending on the application's requirements.

Due to their fundamental role in the design of fault-tolerant distributed systems, consensus protocols have been widely studied. In particular, design and performance issues of indulgent consensus are a research topic that has gained considerable attention. Most of these protocols are asymmetric in the sense that different participants can assume different roles during the execution of the protocol. Usually, there is a process that assumes a "special" role and the others cooperate with it to finish the computation. However, the asymmetric structure of indulgent consensus protocols has a performance pitfall, specially when processes and communication channels are subject to considerable variability in load. The problem is that such protocols use an a priori agreed process ordering to select the process to perform the "special" role. We advocate that adaptive indulgent consensus protocols can be constructed by the introduction of an adaptive process ordering module. In this sense, it is proposed a generic implementation for this module. Based on this generic module we provide implementations of both /spl diams/S- and /spl Omega/-based adaptive indulgent consensus protocols. Further, we investigate their performance by means of simulation and real experiments over a widely distributed system. The experimental results obtained show that the adaptive consensus protocols can outperform their non-adaptive counterparts in as much as 50%.

In this paper, we analyze the performance of consensus protocols based on the rotating coordinator paradigm. We consider a simulated production environment, on which processing and communication resources available for the different processes running the protocols are not necessarily the same. Firstly, we show that, in some scenarios, the performance of the consensus protocol is enhanced when there is an increase in the number and duration of the wrong suspicions periods of the failure detection service used. Since it is well known that wrong suspicions may also decrease the performance of the consensus protocol, a new dilemma is posed to the designers of such protocols. We then propose a new approach to address performance issues in the design of crash-detection based distributed protocols for asynchronous systems. We argue that they must be designed to adapt themselves to the variations on the availability of resources. The concept of slowness oracles is proposed to achieve this goal. Finally, we present a slowness oracle that can be used to transform a non-adaptive consensus protocol into an adaptive one. Simulations show that the adaptive protocol outperforms its conventional non-adaptive counterpart in a number of scenarios, having an equivalent performance in the other scenarios.

A fail-silent node is a self-checking node composed of a number of conventional fail-uncontrolled processors that work together to provide the following fail-controlled behavior: the node either functions correctly or stops functioning after an internal failure is detected. In a software implemented fail-silent node, the non-faulty processors of the node need to execute message order and comparison protocols to keep in step and check each other respectively. In this paper we present a Petri net model for a software implemented fail-silent node specification. Formal analysis by means of occurrence graph is also shown.