Factors contributing to mathematical problem-solving performance: An exploratory study

This paper describes differences in mathematical problem-solving performance of third-grade gifted and fifth-grade average students observed during an eight week period. Results indicated that such factors as attitude, motivation, and belief systems were important to performance. In addition there were major differences in problem-solving behavior between the girls and boys in this study. Because these results were incidental to the original questions of the study (Buchanan, 1984), they were deemed especially significant. Four groups, one of third-grade gifted boys, one of third-grade gifted girls, one of average boys and one of fifth-grade average girls met with the experimenter twice a week for eight weeks to solve a variety of mathematical problems. In the global analysis of video tapes of all sessions and post hoc statistical analysis of selected quantifiable variables, differences in problem-solving performance were best described in terms of motivation, beliefs about mathematics, problem-solving strategies, and means of achieving satisfaction. In addition, the girls' groups were more ego-involved and social; they completed fewer problems and had longer solution times than the boys' groups. Further holistic research is needed to describe the complex interaction that occurs during mathematical problem solving in group situations. Then, appropriate intervention might be designed to assure that both boys and girls have an opportunity to perform at optimum levels.     

Peer feedback mediates the impact of self-regulation procedures on strategy use and reading comprehension in reciprocal teaching groups

The goal of this research was to highlight the role social regulatory processes play in making students’ teamwork in reciprocal teaching (RT) groups (a classroom activity in which students take the teacher’s role in small group reading sessions) effective. In addition to teamwork quality, we expected peer feedback to be a key factor in enhancing students’ reading comprehension achievements. Because previous research (Schünemann et al. in Contemp Educ Psychol 38:289–305, 2013) has shown that procedures of self-regulated learning (SRL) augment the effects of RT methods, we further assumed that such procedures would promote the quality of students’ collaborative efforts. In a cluster-randomized trial, students in 12 fifth-grade classes practiced a strategic approach to reading either in a RT condition or in a RT + SRL condition. In one of the 14 sessions, students’ interactive behavior was videotaped. Strategy use and reading comprehension were assessed at pretest, posttest, and maintenance. Performance differences between conditions were reliable only at maintenance. A multilevel mediation analysis showed that relative to RT students, RT + SRL students were better able to provide their teammates with informative feedback and organize their group work in a task-focused manner. Only feedback quality mediated the sustainability of treatment effects on strategy use and reading comprehension. In essence, this research suggests that effective reading comprehension trainings should integrate explicit instruction and practice in reading strategies, SRL, and focus on supportive peer processes in small groups with extensive instruction and practice in peer feedback.     

Children’s Participation in a Virtual Epidemic in the Science Classroom: Making Connections to Natural Infectious Diseases

This study investigated students’ understanding of a virtual infectious disease in relation to their understanding of natural infectious diseases. Two sixth-grade classrooms of students between the ages of 10 and 12 (46 students) took part in a participatory simulation of a virtual infectious disease, which was integrated into their science curriculum. The results from our analyses reveal that students perceived the simulation as similar to a natural infectious disease and that the immersive components of the simulation afforded students the opportunity to discuss their understandings of natural disease and to compare them to their experiences with the virtual disease. We found that while the virtual disease capitalized on students’ knowledge of natural infectious disease through virtual symptoms, these symptoms may have led students to think of its transfer more as an observable or mechanical event rather than as a biological process. These findings provide helpful indicators to science educators and educational designers interested in creating and integrating online simulations within classroom environments to further students’ conceptual understanding.     

Uncovering influence through Social Network Analysis: the role of schools in Education for Sustainable Development

Abstract

This paper examines the implementation of Education for Sustainable Development (ESD) in Germany and explores the possibilities of Social Network Analysis (SNA) for uncovering influential actors in educational policy innovation processes. From the theoretical perspective, an actor’s influence is inferred from its relative position within issue-specific information flows and the trust placed in its capacities and expertise, instead of relying on an actor’s openly expressed role and policy preferences. Drawing on techniques from quantitative SNA enables to analyse the social interactions as well as the frequency and type of information exchange amongst actors in a particular issue area. Empirically, I focus my attention on the educational innovation of ESD, which has been initiated at the global level, but is mainly put into practice at the national or regional level. Data for the study come from mixed mode interviews with a standardised questionnaire. The interviews were conducted and analysed using egocentric and complete SNA. I find, amongst others results, that NGOs and governmental actors occupy significantly more central, prestigious and influential network positions than schools in the course of implementing ESD in Germany. Furthermore, school representatives exhibit few and weak relations, and mostly share links with other formal education actors.     

Assessing term effectiveness in the interactive information access process

This study addresses the question of whether the way in which sets of query terms are identified has an impact on the effectiveness of users’ information seeking efforts. Query terms are text strings used as input to an information access system; they are products of a method or grammar that identifies a set of query terms. We conducted an experiment that compared the effectiveness of sets of query terms identified for a single book by three different methods. One had been previously prepared by a human indexer for a back-of-the-book index. The other two were identified by computer programs that used a combination of linguistic and statistical criteria to extract terms from full text. Effectiveness was measured by (1) whether selected query terms led participants to correct answers and (2) how long it took participants to obtain correct answers. Our results show that two sets of terms – the human terms and the set selected according to the linguistically more sophisticated criteria – were significantly more effective than the third set of terms. This single case demonstrates that query languages do have a measurable impact on the effectiveness of query term languages in the interactive information access process. The procedure described in this paper can be used to assess the effectiveness for information seekers of query terms identified by any query language.     

试论授课型教学软件的开发与应用

本文根据我国高等学校目前仍以课堂教学为主的现状 ,提出了在重视开发学生自学为主的自学型CAI软件和网络课件的同时不要忽视开发“课堂授课型教学软件”的观点 ,并且结合本校高等数学的教学实践 ,研制开发了“高等数学授课型多媒体教学软件”用于本科教学。通过一年多的教学实践 ,积累了经验 ,找到了不足 ,取得了满意的效果 ,为进一步的研究开发作了有益的探索     

Beginning literacy: links among teacher knowledge, teacher practice, and student learning

Although the importance of phonological awareness has been discussed widely in the research literature, the concept is not well understood by many classroom teachers. In the study described here, we worked with groups of kindergarten and first-grade teachers (the experimental group) during a 2-week summer institute and throughout the school year. We shared with them research about learning disabilities and effective instruction, stressing the importance of explicit instruction in phonological and orthographic awareness. We followed the experimental group and a control group into their classrooms for a year, assessing teachers' classroom practices and their students' (n = 779) learning. The study yielded three major findings: We can deepen teachers' own knowledge of the role of phonological and orthographic information in literacy instruction; teachers can use that knowledge to change classroom practice; and changes in teacher knowledge and classroom practice can improve student learning.     

我国义务教育信息化均衡性评价指标体系的构建及应用

义务教育信息化均衡既是实现我国义务教育均衡发展的有效途径,也是义务教育均衡发展的重要构成因素,因此有必要研究测量工具对义务教育信息化均衡状态进行监测和评估。在借鉴教育均衡评估、教育信息化评估等研究基础上构建的义务教育信息化均衡性评价指标体系,包含“教育信息化投入均衡”、“教育信息化基础设施建设均衡”、“教育信息化应用水平均衡”和“教育信息化人才培养均衡”4项一级指标和24项二级指标。这些指标在北京市义务教育信息化评估中的应用显示：该指标体系具有可行性,评估结论对于现实情况具备一定的诊断性,可为后续建设提供较明确的指导。     

Flow manipulation and cell immobilization for biochemical applications using thermally responsive fluids

A flow redirection and single cell immobilization method in a microfluidic chip is presented. Microheaters generated localized heating and induced poly(N-isopropylacrylamide) phase transition, creating a hydrogel that blocked a channel or immobilized a single cell. The heaters were activated in sets to redirect flow and exchange the fluid in which an immobilized cell was immersed. A yeast cell was immobilized in hydrogel and a 4′,6-diamidino-2-phenylindole (DAPI) fluorescent stain was introduced using flow redirection. DAPI diffused through the hydrogel and fluorescently labelled the yeast DNA, demonstrating in situ single cell biochemistry by means of immobilization and fluid exchange.The ability to control microfluidic flow is central to nearly all lab-on-a-chip processes. Recent developments in microfluidics either include microchannel based flow control in which microvalves are used to control the passage of fluid,¹ or are based on discrete droplet translocation in which electric fields or thermal gradients are used to determine the droplet path.^{2, 3} Reconfigurable microfluidic systems have certain advantages, including the ability to adapt downstream fluid processes such as sorting to upstream conditions and events. This is especially relevant for work with individual biomolecules and high throughput cell sorting.⁴ Additionally, reconfigurable microfluidic systems allow for rerouting flows around defective areas for high device yield or lifetime and for increasing the device versatility as a single chip design can have a variety of applications.Microvalves often form the basis of flow control systems and use magnetic, electric, piezoelectric, and pneumatic actuation methods.⁵ Many of these designs require complicated fabrication steps and can have large complex structures that limit the scalability or feasability of complex microfluidic systems. Recent work has shown how phase transition of stimuli-responsive hydrogels can be used to actuate a simple valve design.⁶ Beebe et al. demonstrated pH actuated hydrogel valves.⁷ Phase transition of thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) using a heater element was demonstrated by Richter et al.⁸ Phase transition was also achieved by using light actuation by Chen et al.⁹ Electric heating has shown a microflow response time of less than 33 ms.¹¹ Previous work¹⁰ showed the use of microheaters to induce a significant shift in the viscosity of thermosensitive hydrogel to block microchannel flow and deflect a membrane, stopping flow in another microchannel. Additionally, Yu et al.¹² demonstrated thermally actuated valves based on porous polymer monoliths with PNIPAAm. Krishnan and Erickson¹³ showed how reconfigurable optically actuated hydrogel formation can be used to dynamically create highly viscous areas and thus redirect flow with a response time of  ～ 2?s. This process can be used to embed individual biomolecules in hydrogel and suppress diffusion as also demonstrated by others.^{15, 16} Fiddes et al.¹⁴ demonstrated the use of hydrogels to transport immobilized biomolecules in a digital microfluidic system. While the design of Krishnan and Erickson is highly flexible, it requires the use of an optical system and absorption layer to generate a geometric pattern to redirect flow.This paper describes the use of an array of gold microheaters positioned in a single layer polydimethylsiloxane (PDMS) microfluidic network to dynamically control microchannel flow of PNIPAAm solution. Heat generation and thus PNIPAAm phase transition were localized as the microheaters were actuated using pulse width modulation (PWM) of an applied electric potential. Additionally, hydrogel was used to embed and immobilise individual cells, exchange the fluid parts of the microfluidic system in order to expose the cells to particular reagents to carry out an in situ biochemical process. The PDMS microchannel network and the microheater array are shown in Figure ​Figure11.Open in a separate windowFigure 1A sketch of the electrical circuit and a microscope image of the gold microheaters and the PDMS microchannels. The power to the heaters was modulated with a PWM input through a H-bridge. For clarity, the electrical circuit for only the two heaters with gelled PNIPAAm is shown (H1 and V2). There are four heaters (V1-V4) in the “vertical channels” and three heaters (H1-H3) in the “horizontal” channel.The microchannels were fabricated using a patterned mould on a silicon wafer to define PDMS microchannels, as described by DeBusschere et al.¹⁷ and based on previous work.¹⁰ A 25 × 75 mm glass microscope slide served as the remaining wall of the microchannel system as well as the substrate for the microheater array. The gold layer had a thickness of 200 nm and was deposited and patterned using E-beam evaporation and photoresist lift-off.²¹ The gold was patterned to function as connecting electrical conductors as well as the microheaters.It was crucial that the microheater array was aligned with an accuracy of  ～ 20μm with the PDMS microchannel network for good heat localization. The PDMS and glass lid were treated with plasma to activate the surface and alignment was carried out by mounting the microscope slide onto the condenser lens of an inverted microscope (TE-2000 Nikon Instruments). While imaging with a 4× objective, the x, y motorized stage aligned the microchannels to the heaters and the condenser lens was lowered for the glass substrate to contact the PDMS and seal the microchannels.Local phase transition of 10% w/w PNIPAAm solution in the microchannels was achieved by applying a 7 V potential through a H-bridge that received a PWM input at 500 Hz which was modulated using a USB controller (Arduino Mega 2650) and a matlab (Mathworks) GUI. The duty cycle of the PWM input was calibrated for each microheater to account for differences in heater resistances (25?Ω to 52?Ω) due to varying lengths of on-chip connections and slight fabrication inconsistencies, as well as for different flow conditions during device operation. Additionally, thermal cross-talk between heaters required decreasing the PWM input significantly when multiple heaters were activated simultaneously. This allowed confining the areas of cross-linked PNIPAAm to the microheaters, allowing the fluid in other areas to flow freely.By activating the heaters in sets, it was possible to redirect the flow and exchange the fluid in the central area. Figure ​Figure22 demonstrates how the flow direction in the central microchannel area was changed from a stable horizontal flow to a stable vertical flow with a 3 s response time, using only PNIPAAm phase transition. Constant pressures were applied to the inlets to the horizontal channel and to the vertical channels. Activating heaters V1-4 (Figure ​(Figure2,2, left) resulted in flow in the horizontal channel only. Likewise, activating heaters H1 and H2 allowed for flow in the vertical channel only. In this sequence, the fluid in the central microchannel area from one inlet was exchanged with fluid from the other inlet. Additionally, by activating heater H3, a particle could be immobilised during the exchange of fluid as shown in Figure ​Figure33 (top).Open in a separate windowFigure 2Switching between fluid from the horizontal and the vertical channel using hydrogel activation and flow redirection with a response time of 3 s. A pressure of 25 mbar was applied to the inlet of the horizontal channel and a pressure of 20 mbar to the vertical channel. The flow field was determined using particle image velocimetry, in which the displacement of fluorescent seed particles was determined from image pairs generated by laser pulse exposure. Processing was carried out with davis software (LaVision).Open in a separate windowFigure 3A series of microscope images near heater H3 showing: (1a)-(1c) A single yeast cell captured by local PNIPAAm phase transition and immobilized for 5 min before being released. (2a) A single yeast cell was identified for capture by embedding in hydrogel. (2b) The cell as well as the hydrogel displayed fluorescence while embedded due to the introduction of DAPI in the surrounding region. (2c) The diffusion of DAPI towards the cell as the heating power of H3 is reduced after 15 min, showing a DAPI stained yeast cell immobilized.Particle immobilisation in hydrogel and fluid exchange in the central area of the microfluidic network were used to carry out an in situ biochemical process in which a yeast cell injected through one inlet was stained in situ with a 4′,6-diamidino-2-phenylindole (DAPI) solution (Invitrogen), which attached to the DNA of the yeast cell.¹⁸ A solution of yeast cells with a concentration of 5 × 10⁷cells/ml suspended in a 10% w/w PNIPAAm solution was injected through the horizontal channel. A solution of 2μg/l DAPI in a 10% w/w PNIPAAm solution was injected through the vertical channel. A single yeast cell was identified and captured near the central heater, and by deactivating the heaters in the vertical channel, DAPI solution was introduced in the microchannels around the hydrogel. After immobilising the cell for 15 min, the heater was deactivated, releasing the cell in the DAPI solution. This process is shown in Figure ​Figure33 (bottom). The sequence of the heater activation and deactivation in order to immobilize the cell and exchange the fluid is outlined in the supplementary material.²¹Eriksen et al.¹⁵ demonstrated the diffusion of protease K in the porous hydrogel matrix,¹⁹ and it was therefore expected that DAPI fluorescent stain (molecular weight of 350 kDa, Ref. ²⁰) would also diffuse. DAPI diffusion is shown in Figure 3(2b) in which the yeast cell shows fluorescence while embedded in the hydrogel. The yeast cell was released by deactivating the central heater and activating all the others to suppress unwanted flow in the microchannel. As a result, the single cell was fully immersed in the DAPI solution. Immobilization of a single cell allows for selection of a cell that exhibits a certain trait and introduction of a new fluid while maintaining the cell position in the field of view of the microscope such that a biochemical response can be imaged continuously.In summary, a microfluidic chip capable of local heating was used to induce phase transition of PNIPAAm to hydrogel, blocking microchannel flow, and thereby allowing for reconfigurable flow. Additionally, the hydrogel was used to embed and immobilise a single yeast cell. DAPI fluorescent stain was introduced using flow redirection, and it stained the immobilized cell, showing diffusion into the hydrogel. The versatile design of this microfluidic chip permits flow redirection, and is suitable to carry out in situ biochemical reactions on individual cells, demonstrating the potential of this technology for forming large-scale reconfigurable microfluidic networks for biochemical applications.