How Engineering Standards are Interpreted and Translated for Middle School

In this exploratory study we examined the alignment of Next Generation Science Standards (NGSS) middle school engineering design standards with lesson ideas from middle school teachers, science education faculty, and engineering faculty (4–6 members per group). Respondents were prompted to provide plain language interpretations of two middle school Engineering Design performance expectations and to provide examples of how the performance expectations could be applied in middle school classrooms. Participants indicated the challenges and benefits of implementing these performance expectations and indicated personal experiences that helped them to interpret the performance expectations. Quality of lessons differed depending on the performance expectation being addressed. Generally, respondents were better able to generate ideas that addressed the paradigm of students ‘‘analyz[ing] data from tests to determine similarities and differences among several design solutions’’ than having students ‘‘define the criteria and constraints of a design problem.’’ A notable finding was the scarcity of quality engineering lesson ideas. The greatest proportion of lessons were categorized as Vague and/or Overly Broad. It appears that NGSS engineering design standards can too easily be decoded in an excessively expansive manner, thus resulting in indefinite ideas that are difficult to translate into classroom practice

Influence of dynamic crosslinking on the morphology, crystallization, and dynamic mechanical properties of PA6,12/EVA blends

This study investigated the effect of dynamic crosslinking of polyamide 6,12 and random copolymers of ethylene and vinyl acetate blends (PA6,12/EVA) on the morphology, crystallinity, and dynamic mechanical properties. The crosslinking agent was dicumyl peroxide (DCP), and the blends were processed in a torque rheometer. The morphology depended on the DCP content, and all blends exhibited the same crystallinity index. However, with increasing crosslinking degree, the interfacial tackiness (E) values increased from 1.8 to 2.7 nm. The lamellar structures of all blends started forming at approximately 160 degrees C, close to the temperature of pure polyamide. The crosslinked phase enhanced the pseudo-elastic behavior of the blends and increased their molecular mobility activation energy. Samples with higher crosslinking degree exhibited smaller permanent deformation (0.01%) than those with low crosslinking.The authors thank Mantova Industria de tubos flexiveis, Retilox quimica for the donation of the materials, and CAPES for a scholarship to Fabricio Bondan. This work was supported by CNPq-National Council for Scientific and Technological Development, Brazil (Grant 473402/2013-0 and 308241/2015-0). The authors also thank the Brazilian Synchrotron Light Laboratory (LNLS) for the use of scientific installations (SAXS1 beamline). J.I.A. is a member of the CICPBA, La Plata, Argentina.info:eu-repo/semantics/publishedVersio