The use of hydroxyapatite as a new inorganic consolidant for damaged carbonate stones

The feasibility and the effectiveness of using hydroxyapatite (HAP) formed by reacting limestone with a solution of diammonium hydrogen phosphate (DAP) in mild conditions, as a consolidant for carbonate stones were investigated. Firstly, a novel method for predamaging limestone was developed. Then, the effects of DAP solution concentration and reaction duration were evaluated to define the best treatment conditions, and the strengthening effect was evaluated on artificially damaged Indiana Limestone samples. Treated samples exhibit a significant increase in the dynamic elastic modulus and tensile strength, which is attributed to microcrack reduction and pore filling consequent to formation of calcium phosphate phases at grain boundaries, as assessed by SEM/EDS and ESEM/EBSD. Consequent to a slight reduction of coarser pores, as revealed by MIP, the sorptivity of treated samples is only slightly reduced, so that water and water vapor exchanges with the environment are not significantly blocked.     

Mathematical Modelling: the Interaction of Culture and Practice

Using a sociocultural approach we analyse the results of a Mexican/British project which investigated the ways in which mathematics is used in the practice of school science and the role of spreadsheets as a mathematical modelling tool. After discussing the different school cultures experienced by two groups of pre-university 16–18 year old students we analyse how these different cultures influenced their practice of mathematics, as well as their work with mathematical spreadsheet modelling activities. There were clear differences between the two groups of students in their preference for external representations, in their understanding of the kind of answers they were expected to produce and in the way they conceived the role of mathematics in the practice of science. Although students preferences for a particular representation were not significantly modified by the use of a spreadsheet as a modelling resource, at the end of the study the students recognised the value of using a more diverse set of representations. The results obtained suggest the possibility of enhancing students' capability to shift between a wider range of representations, including graphical, algebraic and numeric ones, using a modelling approach embedded in a computer environment such as a spreadsheet. This revised version was published online in July 2006 with corrections to the Cover Date.     

Representations of sibling relationships in young children’s literature

Children’s conceptions of what sibling relationships can be like may be influenced, in part, by the literature they read. This study examined the degree to which positive and negative dimensions of sibling relationships were portrayed in a sample of children’s books (n = 261). We also investigated how mothers and fathers were depicted when responding to sibling conflict. Results indicated that although children’s books often represent warmth and involvement between siblings, they rarely described children engaging in conflict management or relational maintenance activities. Parents were predominantly portrayed as responding to children’s conflict using controlling methods rather than techniques that might foster negotiation and problem solving. Characters who were middle children are under-represented in children’s literature. Results are discussed in terms of how educators can select, use, and adapt books in their efforts to help strengthen children’s sibling relationships.     

Camila,the earth,and the sun: Constructing an idea as shared intellectual property

Recent research has challenged traditional assumptions that scientific practice and knowledge are essentially individual accomplishments, highlighting instead the social nature of scientific practices, and the co‐construction of scientific knowledge. Similarly, new research paradigms for studying learning go beyond focusing on what is “in the head” of individual students, to study collective practices, distributed cognition, and emergent understandings of groups. These developments require new tools for assessing what it means to learn to “think like a scientist.” Toward this goal, the present case study analyzes the discourse of a 6th‐grade class discussing one student's explanation for seasonal variations in daylight hours. The analysis identifies discourse moves that map to disciplinary practices of the social construction of science knowledge, including (1) beginning an explanation by reviewing the community's shared assumptions; (2) referencing peers' work as warrants for an argument; and (3) building from isolated ideas, attributed to individuals, toward a coherent situation model, attributed to the community. The study then identifies discourse moves through which the proposed explanation was taken up and developed by the group, including (4) using multiple shared representations; (5) leveraging peers' language to clarify ideas; and (6) negotiating language and representations for new, shared explanations. Implications of this case for rethinking instruction, assessment, and classroom research are explored. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 47:619–642, 2010     

How do secondary students approach different types of division with remainder situations? Some evidence from Spain

Division-With-Remainder (DWR) problems are particularly complex, as suggested in many studies. The purpose of this work was to establish whether students’ difficulties in DWR problems came from an inadequate initial representation or from an inadequate final interpretation of the numerical answers, and whether remainders could be grouped into two blocks depending on the kind of answer, either directly matching the terms of the division or not. Forty-five Spanish secondary students, aged 12–13, were requested to solve two Types of Division Situations (i.e., Equal Groups and Comparison), each one involving four Types of Remainder (i.e., Remainder-Not-Divisible, Remainder-Divisible, Remainder-as-the-Result, and Readjusted-Quotient-by-Partial-Increments). Our data showed that: (a) the selection of the correct solution procedure depended on the Type of Division Situations, being easier in Equal Groups than in Comparison problems; (b) correct interpretations were higher than the percentages reported in other researches; and (c) success in problems whose answers were the quotient or the remainder was higher than in Readjusted-Quotient-by-Partial-Increments problems. The results obtained suggest that students’ difficulties originate in the initial representation of the DWR problems and that it would be more adequate to refer to the difficulty of Readjusted-Quotient-by-Partial-Increments problems in particular, rather than to the difficulty of DWR problems in general.     

A developmental approach to the risk of a first recurrence in child protective services

The objective of this study is to estimate the risk of a first recurrence over a five-year period following initial child protective services (CPS) intervention and identify the characteristics associated with the risk of recurrence for three different age groups. Recurrence is defined as the first substantiated report within the observation period after initial services have ended. The study involved a cohort of 25,897 Quebec children who received postinvestigation services for the first time and whose cases were closed between 2005 and 2009. Survival analysis was used to estimate the five-year risk of recurrence and Cox regression to model the risk of recurrence for three age groups. The covariates introduced into the regression analyses were characteristics of the child and initial services. The risk of recurrence in the five years following termination of initial CPS services was 36% for the entire cohort and varied depending on the child's age at the time of case closure. Children aged 6–11 when their cases were closed had the highest risk of recurrence. Although Aboriginal descent and prior CPS investigations have a consistent effect on the risk of recurrence in all three age groups, the effects of other covariates, such as out-of-home placement and court involvement, vary or are even reversed, depending on the child's age. These findings highlight the need to adopt a differential approach that takes into account the child's age, both in the provision of protective services and in research involving the population receiving such services.     

Emergent literacy profiles among prekindergarten children from low-SES backgrounds: Longitudinal considerations

This study represents a longitudinal follow-up to a prior investigation that identified five profiles of emergent literacy skills among children in the fall of their prekindergarten year. Here, we examined: (a) how profile patterns changed from fall to spring, (b) the extent to which children remained stable in their profile membership, and (c) possible factors that may explain children's movement in profile membership from fall to spring. Participants were 484 children enrolled in needs-based programs. Eight measures of emergent literacy, across oral language and code-related domains, were administered in both the fall and the spring of the prekindergarten year. Latent profile analysis was used to classify children into fall and spring profiles (N = 484, 369, respectively). Although there were fewer profiles identified in the spring, children's membership within the profiles was characterized by a degree of stability, especially in the extremes of performance. Among children who shifted membership from fall to spring (35%), movement to a more desirable profile was primarily associated with children's emergent literacy skills, particularly oral language, at the beginning of the prekindergarten year.     

‘Critical friends’: exploring arm’s length actor relationships to local government in education

Abstract

Discussions charting the changing role of local government in education have often focused extensively on ‘concrete’ policy changes over time, but have provided less detail on the contribution to changing power relations of less tangible shifts. Drawing on Foucauldian notions of discourse and governmentality, in this paper, detailed rationalities of local third-sector and other ‘arm’s length’ actors in English education are explored, with a focus on their relationship to local authority (LA) school admissions teams. The paper aims to provide deeper understanding of tactical struggles for authority which happen within competitive local sociopolitical spaces. Data is utilised from a study of ‘Choice Advice’ (CA) in 10 LAs, within a background context where arm’s length agents deployed to deliver CA have been co-opted into central government marketisation regimes, but local state planning of schooling is arguably more equitable for vulnerable families than are logics advancing a marketisation of education. The research reveals: (1) discourses valourising ‘independence’ and ‘distance’ from local state ‘agendas’; (2) discourses separating the interests of ‘parents’ and ‘schools’, with LAs positioned as representing the latter; (3) dehumanising representations of LA officers as ‘faceless’, obstructive and requiring regulation from ‘critical friends’.     

Parental Mediation of Children's Internet Use

This article examines parental regulation of children and teenagers' online activities. A national survey of 1511 children and 906 parents found that 12–17-year-olds encounter a range of online risks. Parents implement a range of strategies, favoring active co-use and interaction rules over technical restrictions using filters or monitoring software, but these were not necessarily effective in reducing risk. Parental restriction of online peer-to-peer interactions was associated with reduced risk but other mediation strategies, including the widely practiced active co-use, were not. These findings challenge researchers to identify effective strategies without impeding teenagers' freedom to interact with their peers online.