The web offers rich learning resources, including technology education. With the advocate of hands-on learning and STEM education, many web videos teach users how to use technological tools to create an STEM artifacts and acquire related science knowledge. These videos were adopted by teachers in their classroom and followed closely as pro-claimed technology education. As web credibility is a challenge and how students approach the topics to develop systematic knowledge are crucial, this study proposed a learning model to address these challenges. The model was embedded into a teacher training to have teachers self-experience these challenges. Participating teachers were expected to construct their pedagogical knowledge inductively, and their responses to the proposed learning were collected. With the participation of 27 in-service teachers, the results demonstrated teachers’ recognition and support of the proposed model. However, their belief and concerns regarding its implementation generated uncertainty. Study results broaden the spectrum of hands-on teacher training.
Abstract. Design and analysis of a new Abbé free coplanar xy stage are presented in this paper. The xy stage is formed as conventional xy stages which combine with two stacked up linear guides. The x-guide is on the bottom and the y-guide is on top of the x-guide. The travel range of this xy stage is 300mm x 300mm, which fits dimensions of 12-inch wafers. A special mechanism is designed such that the z-surface of the y-guide has the same height as the zsurface of x-guide, and the Abbé error and cumulative error of this coplanar stage can be reduced. The concept of symmetric structure design is also considered to eliminate the structural deformation due to driving force of two guides. For this long travel range precision stage, the finite element method (FEM) is applied to analyze the structural deformation and vibration natural frequencies. The requirement of structural deformation due to self-weight load is limited to 1.5µm, and first natural frequency is limited to over 100 Hz.
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