The fine structural appearance of Z-disk lattices in vertebrate skeletal "fast" muscle varies depending upon whether osmium or glutaraldehyde has been employed as the primary fixative. Prior investigators have attributed the differences to change in the extent of actin filament overlap within the Z-disk and/or to rearrangement of Z-disk filaments.Adult frog and young newt "fast" muscle has been studied under various degrees of stretch, with several different aldehyde and osmium fixation procedures, and after plastic section digestion techniques utilizing Pronase or pepsin. Serial cross sections of Z-disks were correlated with oriented cross and longitudinal sections. Fixation with collidine-buffered osmium and Verona1 acetate-buffered glutaraldehyde seems to provide the greatest and most distincitly contrasting differences. A consistently arranged phase, the filamentous lattice, can be discerned after either fixation. However, a second phase, termed "Z-disk matrix," appears variable, perhaps due to extraction during primary osmium fixation procedures. Glutaraldehyde-fixed frog muscle Z-disks display a copious matrix, one which is seldom totally depleted by osmium fixation. In young newt muscle Z-disks, little matrix is present after glutaraldehyde fixation and none of it remains after primary osmium. In Z-disks fixed by either method, matrix that is retained appears to be deposited in lattice-like patterns. It is suggested that these matrix patterns, or their loss, are the basis for the varying images of Z-disks observed under different fixation conditions, and that the filamentous lattice js relatively stable. The Z-disk is more rapidly obliterated by Pronase or pepsin digestion than is any other muscle component, including actin (which appears notably unreactive). The rapid digestion effect is limited to the region postulated to include the matrix phase. Models for the structural interrelationship of filamentous and matrix phases are discussed and compared to prior Z-disk models.

Based on recent research in fluency instruction, the authors present a scenario in which a teacher focuses her fluency instruction on authentic fluency tasks based in performance. Beginning with establishing a student-friendly definition of fluency and culminating with student engagement in fun fluency activities, this article explores the possibilities for bringing joy back into repeated reading practice. Directions for creating a fun fluency kit for classroom use are included

Reframing the preparation of early childhood educators from “training” to an induction into a profession of practice, this chapter outlines a blueprint for such a paradigm shift. Induction involves embedded structures and opportunities for preservice early educators to develop as professionals, including core foundational knowledge about child development as well as apprenticeship in practice. Professionalizing the field is grounded in early educators' deep understanding of the child's sociocultural milieu and the implications for development and learning. Further, to mitigate the effects of trauma that has become emblematic of the recent pandemic, aspiring early educators need explicit instruction and support as they co-construct the profession within their courses, field experiences, and co-curricular activities.

Comprehension strategy instruction has been widely studied in the past 10 years. We now know that students who actively engage and interact with text using particular cognitive strategies are more likely to understand and remember more of what they have read. Students who use these strategies are able to access knowledge that is outside the realm of their personal experience. These cognitive strategies have historically been successfully taught to students in the upper grades. However, until recently, there has been very little research that exists which examines the efficacy of teaching comprehension strategies and facilitating their use with emergent readers. This article depicts the teaching of these strategies in a kindergarten classroom and the resulting possibilities and explorations that occurred following successful strategy instruction