Exploring the Roles and Nature of Science: A case study of severe acute respiratory syndrome

The roles of science in society and the nature of science are the focus of many science curricula. Current views about these two aspects of science have largely been informed by the history of scientific development. This article uses the outbreak of severe acute respiratory syndrome—a recent health scare—as a case study to explore the roles of science and their relationship with the nature of science and societal factors. The review provides deeper insight into the difficulties that are encountered in fulfilling these roles, particularly those that relate to the nature of science. This review has implications for both school and public science education.     

High-throughput particle manipulation by hydrodynamic,electrokinetic, and dielectrophoretic effects in an integrated microfluidic chip

Integrating different steps on a chip for cell manipulations and sample preparation is of foremost importance to fully take advantage of microfluidic possibilities, and therefore make tests faster, cheaper and more accurate. We demonstrated particle manipulation in an integrated microfluidic device by applying hydrodynamic, electroosmotic (EO), electrophoretic (EP), and dielectrophoretic (DEP) forces. The process involves generation of fluid flow by pressure difference, particle trapping by DEP force, and particle redirect by EO and EP forces. Both DC and AC signals were applied, taking advantages of DC EP, EO and AC DEP for on-chip particle manipulation. Since different types of particles respond differently to these signals, variations of DC and AC signals are capable to handle complex and highly variable colloidal and biological samples. The proposed technique can operate in a high-throughput manner with thirteen independent channels in radial directions for enrichment and separation in microfluidic chip. We evaluated our approach by collecting Polystyrene particles, yeast cells, and E. coli bacteria, which respond differently to electric field gradient. Live and dead yeast cells were separated successfully, validating the capability of our device to separate highly similar cells. Our results showed that this technique could achieve fast pre-concentration of colloidal particles and cells and separation of cells depending on their vitality. Hydrodynamic, DC electrophoretic and DC electroosmotic forces were used together instead of syringe pump to achieve sufficient fluid flow and particle mobility for particle trapping and sorting. By eliminating bulky mechanical pumps, this new technique has wide applications for in situ detection and analysis.     

Cognitive load in percentage change problems: unitary,pictorial, and equation approaches to instruction

Eighth grade students in Australia (N = 60) participated in an experiment on learning how to solve percentage change problems in a regular classroom in three conditions: unitary, pictorial, and equation approaches. The procedure involved a pre-test, an acquisition phase, and a post-test. The main goal was to test the relative merits of the three approaches from a cognitive load perspective. Experimental results indicated superior performance of the equation approach over the unitary or pictorial approach especially for the complex tasks. The unitary approach required students not only to process the interaction between numerous elements within and across solution steps, but also to search for critical information, thus imposing high cognitive load. The pictorial approach did not provide a consistent approach to tackling various percentage change problems. Coupled with the need to coordinate multiple elements within and across solution steps, and the need to search for relevant information in the diagram, this approach imposed high cognitive load. By treating the prior knowledge of percentage quantity as a single unit, the equation approach required students to process two elements only. Empirical evidence and theoretical support favor the equation approach as an instructional method for learning how to solve percentage change problems for eighth graders.     

远亲不如近邻

关于邻居的概念,于我而言,更多的是有关童年和少年时的回忆。或许很多人有着与我相似的人生轨迹:童年和少年时期享受着亲密、欢乐的邻里生活;求学时期的后半段离开故土,"邻居"的身份是与"室友"合二为一的;工作后,作为一个"异乡人","邻居"两个字显得最为淡薄,它代表着不同居所里一扇扇紧锁的门,没有感情色彩,拒人于千里。如今,在这个城市安了家,左邻右里,一边是新搬来的租户,一边是一户偶尔住上两三天的人家,还有一户因为刚刚换了"学位房"而搬走了,当然,楼道里更多的是几年来连头也没点过的陌生人。很多时候,走出电梯,看到那一扇比一扇扎实的大铁门,我心中总会泛起一种焦虑,仿佛自己依然是这个城市里多余的"入侵者"。人们总说,儿时的记忆是最深刻的,感受亦然。或许终有一天,我们还能找回一个地方,大家都敞开着大门,等待邻居们一一探索……     

Chinese students’ science-related experiences: Comparison of the ROSE study in Xinjiang and Shanghai

Background: Students’ daily-life experiences may render favorable effects on the students’ affective domain like interest, enthusiasm, motivation, joy, curiosity, awareness, and eagerness to learn science as not commonly found in the classroom environment. However, no rigorous research has been reported on those aspects in Mainland China despite many recent studies done in various Western countries.

Purpose: This paper aims to report and compare the science-related experiences of ninth-graders from two places (in Urumqi City of Xinjiang province and Shanghai) in China through a large-scale survey of their junior secondary three students.

Sample: The sample consists of 4115 students in Urumqi City (from 28 schools) and Shanghai (from 25 schools).

Design and methods: This study adopted a Likert scale questionnaire instrument, as translated from the international Relevance Of Science Education (ROSE) Project. From a confirmatory factor analysis of the data, we identify and focus on six factors which are directly correlated with students’ science-related experiences outside school environment in Xinjiang and Shanghai and employ relevant factor scores to compare the gender, regional, and socioeconomic effects.

Results: As revealed by the t-test, gender and regional differences were statistically significant in affecting (1) students’ outdoor living experience, (2) hands-on experience of transportation, and (3) their daily-life experience with do-it-yourself tools and models. In all three aspects, boys and Xinjiang students possessed richer experiences than girls and Shanghai students, respectively.

Conclusions: Based on ANOVA tests, Shanghai students’ out-of-school science-related experiences were more often significantly affected by various socioeconomic variables (including their parents’ education and occupation and their family income) than Xinjiang students. From cross-regional comparison, Chinese students had much fewer science-related experiences than those of Greek and Finnish students. The limitations and educational implications of the present study are also discussed.     

Induced charge electro osmotic mixer: Obstacle shape optimization

Efficient mixing is difficult to achieve in miniaturized devices due to the nature of low Reynolds number flow. Mixing can be intentionally induced, however, if conducting or nonconducting obstacles are embedded within the microchannel. In the case of conducting obstacles, vortices can be generated in the vicinity of the obstacle due to induced charge electro-osmosis (ICEO) which enhances mixing of different streams: the obstacle shape affects the induced zeta potential on the conducting surface, which in turn influences the flow profile near the obstacle. This study deals with optimization of the geometric shape of a conducting obstacle for the purpose of micromixing. The obstacle boundary is parametrically represented by nonuniform rational B-spline curves. The optimal obstacle shape, which maximizes the mixing for given operating conditions, is found using genetic algorithms. Various case studies at different operating conditions demonstrated that the near right triangle shape provides optimal mixing in the ICEO flow dominant regime, whereas rectangular shape is the optimal shape in diffusion dominant regime. The tradeoff between mixing and transport is examined for symmetric and nonsymmetric obstacle shapes.     

Syntactic skills in sentence reading comprehension among Chinese elementary school children

The present study examined the role of syntactic skills for reading comprehension in Chinese. Two hundred and seventy-two Chinese children were tested on their phonological processing, orthographic, morphological, syntactic, and literacy skills at Grades 1 and 2. Hierarchical multiple regression results showed that syntactic skills, in terms of word order, connective usage, and knowledge of morphosyntactic structure (measured by an oral cloze task) in Grade 1, significantly predicted sentence reading comprehension in Grade 2 after controlling for the children’s age, IQ, and word level reading-related cognitive skills in Grade 1, and word reading in Grade 2. As in alphabetic languages, syntactic skills are essential for reading comprehension in Chinese. The unique roles of individual syntactic skills for understanding sentences in Chinese are discussed.     

Ninth Graders’ Learning Interests, Life Experiences and Attitudes Towards Science & Technology

Students’ learning interests and attitudes toward science have both been studied for decades. However, the connection between them with students’ life experiences about science and technology has not been addressed much. The purpose of this study is to investigate students’ learning interests and life experiences about science and technology, and also their attitudes toward technology. A total of 942 urban ninth graders in Taiwan were invited to participate in this study. A Likert scale questionnaire, which was developed from an international project, ROSE, was adapted to collect students’ ideas. The results indicated that boys showed higher learning interests in sustainability issues and scientific topics than girls. However, girls recalled more life experiences about science and technology in life than boys. The data also presented high values of Pearson correlation about learning interests and life experiences related to science and technology, and in the perspective on attitudes towards technology. Ways to promote girls’ learning interests about science and technology and the implications of teaching and research are discussed as well.