Student absences during learning cycle phases: a technological alternative for make-up work in laboratory based high school chemistry

Absences from school present a major obstacle to students' gaining understandings of concepts developed in class. Moreover, teachers' finding effective ways for students to make up missed work is a continual problem, especially for laboratory-based science classes. In an exploratory study, we investigated an alternative procedure for making up missed class work: viewing a quasi-interactive videotaped presentation of missed portions of a learning cycle in chemistry. Two treatment groups were involved. One group of students completed data sheets while watching a videotape, then wrote answers to questions posed by the videotaped instructor. This procedure simulated make-up work. A second group of students participated in a conventional learning cycle: exploration, conceptual invention and concept application. Results demonstrate that teachers can videotape investigations to conveniently and effectively use as make-up assignments for a chemistry learning cycle.     

Differentiating between and synthesizing quantitative,qualitative, and longitudinal research on polarized school cultures: a comment on Van Houtte (2006)

Van Houtte provides a valuable large‐sample quantitative analysis of differentiation and polarization processes between and within school cultures in Belgium. Such research across 34 secondary schools provides greater confidence that the findings in the ethnographic tradition for the differentiation–polarization theory are not due to idiosyncracies of the individual schools chosen. However, it is unhelpful to contrast her large‐sample approach with the ethnographic tradition by characterizing the former as quantitative and the latter as qualitative. Many ethnographic studies of secondary schools have employed quantitative methods. It is better to characterize her research as multi‐site and the ethnographic tradition as case‐study. This illuminates how the two methodologies can be more constructively synthesized. Within large sample multi‐site approaches some selection of in‐depth case studies, together with longitudinal data analysis, are needed to disentangle socio‐economic class effects from differentiation effects in order to determine causality.     

The Genetic Drift Inventory: A Tool for Measuring What Advanced Undergraduates Have Mastered about Genetic Drift

Understanding genetic drift is crucial for a comprehensive understanding of biology, yet it is difficult to learn because it combines the conceptual challenges of both evolution and randomness. To help assess strategies for teaching genetic drift, we have developed and evaluated the Genetic Drift Inventory (GeDI), a concept inventory that measures upper-division students’ understanding of this concept. We used an iterative approach that included extensive interviews and field tests involving 1723 students across five different undergraduate campuses. The GeDI consists of 22 agree–disagree statements that assess four key concepts and six misconceptions. Student scores ranged from 4/22 to 22/22. Statements ranged in mean difficulty from 0.29 to 0.80 and in discrimination from 0.09 to 0.46. The internal consistency, as measured with Cronbach''s alpha, ranged from 0.58 to 0.88 across five iterations. Test–retest analysis resulted in a coefficient of stability of 0.82. The true–false format means that the GeDI can test how well students grasp key concepts central to understanding genetic drift, while simultaneously testing for the presence of misconceptions that indicate an incomplete understanding of genetic drift. The insights gained from this testing will, over time, allow us to improve instruction about this key component of evolution.     

Navigating complexity,culture, collaboration,and emotion: student perspectives on global justice and global justice education

Recent years have seen increasing scholarly attention to the ways in which colleges and universities might contribute to educating ‘global citizens’ who work toward addressing injustice and inequity. The present study examines the experiences and perspectives of students participating in an upper level ‘global justice inquiry’ course designed to help meet this goal. Drawing from interviews with students and reflections submitted as part of their course assessment, we explore participants’ developing understanding of global justice and their experiences of learning about this topic. This investigation reveals key issues that students highlight and with which they sometimes struggle, including the complexity of global challenges, the importance of collaboration in attempting to address such challenges, the significance of navigating cultural considerations, and the potential influence of emotion on understanding and action. Implications of these findings, including the potential value of considering these issues as threshold concepts in global justice education, are discussed.     

Motivation and Engagement with Physics: a Comparative Study of Females in Single-Sex and Co-educational Classrooms

Research in Science Education - It has been argued that the establishment of single-sex classes for females can increase their motivation and participation in physics. This paper reports on...     

Novel on-demand droplet generation for selective fluid sample extraction

A novel microfluidic device enabling selective generation of droplets and encapsulation of targets is presented. Unlike conventional methods, the presented mechanism generates droplets with unique selectivity by utilizing a K-junction design. The K-junction is a modified version of the classic T-junction with an added leg that serves as the exit channel for waste. The dispersed phase fluid enters from one diagonal of the K and exits the other diagonal while the continuous phase travels in the straight leg of the K. The intersection forms an interface that allows the dispersed phase to be controllably injected through actuation of an elastomer membrane located above the inlet channel near the interface. We have characterized two critical components in controlling the droplet size-membrane actuation pressure and timing as well as identified the region of fluid in which the droplet will be formed. This scheme will have applications in fluid sampling processes and selective encapsulation of materials. Selective encapsulation of a single cell from the dispersed phase fluid is demonstrated as an example of functionality of this design.