Highlighting hybridity: A critical discourse analysis of teacher talk in science classrooms

There is evidence that alienation from science is linked to the dominant discourse practices of science classrooms (cf. Lemke, J. L. (1990). Talking Science: Language, Learning, and Values. Norwood, NJ: Ablex). Yet, in secondary science education it is particularly hard to find evidence of curriculum reform that includes explicit changes in pedagogic discourses to accommodate the needs of students from a wide range of backgrounds. However, such evidence does exist and needs to be highlighted wherever it is found to help address social justice concerns in science education. In this article, I show how critical discourse analysis can be used to explore a way of challenging the dominant discourse in teacher-student interactions in science classrooms. My findings suggest a new way of moving toward more socially just science curricula in middle years and secondary classrooms by using hybrid discourses that can serve emancipatory purposes. © 2005 Wiley Periodicals. Inc.

Variation talk: Articulating meaning in statistics

Little is known about the way that teachers articulate notions of variation in their own words. The study reported here was conducted with 17 prospective secondary math and science teachers enrolled in a preservice teacher education course which engaged them in statistical inquiry of testing data. This qualitative study examines how these preservice teachers articulated notions of variation as they compared two distributions. Although the teachers made use of tandard statistical language, they also expressed rich views of variation through nonstandard terminology. This paper details the statistical language used by the rospective teachers, categorizing both standard and nonstandard expressions. Their nonstandard language revealed strong relationships between expressions of variation and expressions of distribution. Implications and the benefits of nonstandard language in statistics are outlined.

Functional cross-talk between cytokine receptors revealed by activating mutations in the extracellular domain of the beta-subunit of the GM-CSF receptor

Several reports have suggested an interaction between the erythropoietin receptor (EpoR) and the shared signaling subunit (hbeta(c)) of the human granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin (IL)-3, and IL-5 receptors, although the functional consequences of this interaction are unclear. We previously showed that in vivo expression of constitutively active extracellular (EC) mutants of hbeta(c) induces erythrocytosis and Epo independence of erythroid colony-forming units (CFU-E). This occurs despite an apparent requirement of these mutants for the GM-CSF receptor alpha-subunit (GMRalpha), which is not expressed in CFU-E. Here, we show that coexpression of hbeta(c) EC mutants and EpoR in BaF-B03 cells, which lack GMRalpha, results in factor-independent proliferation and JAK2 activation. Mutant receptors that cannot activate JAK2 fail to produce a functional interaction. As there is no detectable phosphorylation of hbeta(c). on intracellular tyrosine residues, EpoR displays constitutive tyrosine phosphorylation. These observations suggest that JAK2 activation mediates cross-talk between EC mutants of hbeta(c) and EpoR. The implications of these data are discussed as are our findings that activated hbeta(c) mutants can functionally interact with certain other cytokine receptors.