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This study aimed to explore learners’ discourse patterns and outcomes while using a visible-annotation tool as a collaborative representation tool. The tool used in this study introduced two types of sharing activities before the problem-solving phase to support sequential knowledge construction. Forty participants were randomly assigned to one of three groups according to two variables: type of sharing activities (meaning sharing activity (M) and opinion sharing activity (O)), and type of representation function to guide sharing activities (word-based function (W) and sentence-based function (S)). All three groups performed sharing activities during the same period. After completing these, the participants carried out a lesson-planning task in pairs during the problem-solving phase. All annotations across three learning phases were categorised to investigate discourse patterns. The findings revealed that Group MWOS, provided with M based on W and O based on S, had the most effective knowledge construction process, showing sequential discourse patterns. In addition, differences in discourse patterns among groups positively influenced the level of collaborative outcomes.

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An arc array slit is used for generating the focused Lamb wave by laser, where spatially expanded Nd:YAG pulse laser is illuminated through the arc array slit on the surface of a sample plate to generate the Lamb wave of the same pattern as the slit. Then the generated Lamb wave is focused at the focal point of which distance from the slit position is dependent on the curvature of slit arc. The focusing effect enables to acquire higher intensity of wave at the focus, better SNR in the received signal, and improved spatial resolution than when we use the conventional line array slit. This paper proposes a new imaging technique using this laser-generated focused Lamb-wave, which gives more accurate information about the size and the location of defects in thin plate. In order to verify the usefulness of the proposed method, experiments is carried out for the detection of the artificial linear and circular defects on a thin aluminum plate.