A content analysis of the presentation of the mole concept in chemistry textbooks

The goal of this study was to examine the means used by textbook authors to introduce, define, and explain the mole concept in high school and introductory college chemistry textbooks. The analysis was framed by four questions:

• 1 How is the mole defined?
• 2 What concepts about the atom are introduced prior to the mole?
• 3 Is Avogadro's constant presented as an experimentally determined value?
• 4 What is the context for introducing the mole?

Twenty-nine high school and introductory college level chemistry texts were examined. After independent reading of appropriate sections of each text, discussion of differences, second or third readings of texts, and subsequent discussions, both authors reach 100% agreement concerning the results. Major conclusions were

• 1 Two ways of defining the mole dominate the texts. One way defines the mole as Avogadro's number (6.02 × 10²³) particles; the other method defines the mole in terms of carbon-12.
• 2 All texts that present a definition in terms of C-12 introduce and define concepts about the atom prior to introducing the mole.
• 3 Most texts at all levels point out that the value 6.02 × 10²³ is an experimentally determined quantity.
• 4 Nearly all texts discuss the mole in relation to die problem of finding a way to count particles that are too small to be directly weighed. Most texts also use a familiar counting unit, such as the dozen, to introduce the mole by analogy.

Four issues were discussed: (a) the defining attributes of the mole concept itself and the cognitive requirements for comprehending the two most frequently used definitions; (b) the connection between the definition of the mole presented in the text and the concepts about atoms that are introduced before the mole concept is developed; (c) the experimental nature of Avogadro's number; and (d) the context or setting for developing the mole concept.     

The recognition of facial expressions in the first two years of life: mechanisms of development

In recent years the infant's ability to recognize facial expressions of emotion has attracted considerable attention from developmental psychologists. The rationale guiding much of this research has been that this ability plays an important role in later socioemotional development. In the present article, the research relating to this topic is reviewed and synthesized. It is concluded that the recognition of facial expressions develops slowly over the first 2 years of life, and that even at the end of the second year the infant's understanding of facial expressions is still quite rudimentary. Following this review is a discussion of 2 unresolved issues regarding the development of this ability. 1 issue relates to the biological/experimental basis on which the ability to recognize facial expressions develops. Research with primates is brought to bear on this point, and useful analogues with human infants are sought. From this research it is suggested that a component of the ability to recognize facial expressions is unlearned, although experience of some as yet undetermined nature affects this biological readiness. The second issue relates to the possible neurological mechanisms that mediate this ability. Research with primates, normal adults, and brain damaged adults is used to support the speculation that a posterior region of the right hemisphere is responsible for mediating the recognition of facial expressions.     

Pre-service physical education teachers’ Indigenous knowledge,cultural competency and pedagogy: a service learning intervention

In this paper, we investigate the effects of a community- and school-based service learning experience (SLE) on pre-service physical education teachers’ Indigenous knowledge, cultural competency and pedagogy. Informed by the theoretical tenets of Indigenous research methodologies, experiential learning and critical reflection, we examine 55 final-year pre-service physical education teachers’ (age: 21.9 [8.3]; 10.7% low SES; 68% females) cultural learning and competency in a core unit of study with a six-week SLE. Measures of their experiences included reflective journals, multicultural teaching competency scales and focus group interviews. Findings support the design of the SLE, with statistically significant changes in pre-service teachers’ perceptions of their cultural competency (p < 0.001). Pre-service teachers were able to challenge their assumptions about Indigenous students, plan and implement student-centred and culturally relevant pedagogies. Attention is drawn to the design of this SLE and demonstrates the importance of using Indigenous community members and teachers as mentors, which has not been explored in previous SLE studies.     

Teachers' education, classroom quality, and young children's academic skills: results from seven studies of preschool programs

In an effort to provide high-quality preschool education, policymakers are increasingly requiring public preschool teachers to have at least a Bachelor's degree, preferably in early childhood education. Seven major studies of early care and education were used to predict classroom quality and children's academic outcomes from the educational attainment and major of teachers of 4-year-olds. The findings indicate largely null or contradictory associations, indicating that policies focused solely on increasing teachers' education will not suffice for improving classroom quality or maximizing children's academic gains. Instead, raising the effectiveness of early childhood education likely will require a broad range of professional development activities and supports targeted toward teachers' interactions with children.     

Marital conflict and conduct problems in Children of Twins

The Children-of-Twins design was used to test whether associations between marital conflict frequency and conduct problems can be replicated within the children of discordant twin pairs. A sample of 2,051 children (age 14-39 years) of 1,045 twins was used to estimate the genetic and environmental influences on marital conflict and determine whether genetic or environmental selection processes underlie the observed association between marital conflict and conduct problems. Results indicate that genetic and nonshared environmental factors influence the risk of marital conflict. Furthermore, genetic influences mediated the association between marital conflict frequency and conduct problems. These results highlight the need for quasiexperimental designs in investigations of intergenerational associations.