Using Science Lessons to Promote Collaborative Problem Solving : Focus on the Knowledge-Constructive Jigsaw Method

本研究の目的は，協働的問題解決を生起させる中学校理科の授業の特徴を見出すことである。そこで，「知識構成型ジグソー法」に着目して，その手法を用いた先行の授業実践の分析や文献調査によって検討して，「知識構成型ジグソー法」を用いた中学校理科授業の特徴を明らかにした。また，「知識構成型ジグソー法」を用いた授業をデザインして実践することで，その有用性を検証した。This study aimed to investigate methods promote collaborative problem solving in junior high school science classes. Our focus was on the knowledge-constructive jigsaw method. We reviewed the literature on teaching methods in science classes. In the process, we noted good examples of such methods and identified key points made by various research groups. We ran pilot classes to test the ideas we had developed as a result. We introduced the knowledge-constructive jigsaw method into teaching practice

Thermal Dehydration of Magnesium Acetate Tetrahydrate: Formation and in Situ Crystallization of Anhydrous Glass

The kinetics and mechanism of the thermal dehydration of magnesium acetate tetrahydrate were investigated as a typical example of the glass formation process via the thermal decomposition of solids. Formation of an intermediate fluid phase was identified as the characteristic phenomenon responsible for the formation of anhydrous glass. Thermal dehydration from the surface fluid layer regulates the zero-order-like rate behavior of the mass-loss process with an apparent activation energy <i>E</i>_a ≈ 70–80 kJ mol^–1. Because of variations in the mechanism of release of the water vapor with changes in the reaction temperature range, the mass-loss behavior is largely dependent on the particle size of the sample and heating conditions. The formation of hollow anhydrous glass is the novel finding of the present study. The mechanism of formation is discussed in terms of complementary interpretations of the morphological changes and kinetic behavior of the thermal dehydration. On further heating, the as-produced anhydrous glass exhibits a glass transition phenomenon at approximately 470 K with an <i>E</i>_a ≈ 550–560 kJ mol^–1, and subsequently crystallizes via the three-dimensional growth of nuclei controlled by diffusion. The crystallization process is characterized by an <i>E</i>_a ≈ 280 kJ mol^–1 and an enthalpy change Δ<i>H</i> = −13.3 kJ mol^–1, resulting in the formation of smaller, rounded particles of crystalline anhydrate

Thermal Dehydration of Magnesium Acetate Tetrahydrate: Formation and in Situ Crystallization of Anhydrous Glass

The kinetics and mechanism of the thermal dehydration of magnesium acetate tetrahydrate were investigated as a typical example of the glass formation process via the thermal decomposition of solids. Formation of an intermediate fluid phase was identified as the characteristic phenomenon responsible for the formation of anhydrous glass. Thermal dehydration from the surface fluid layer regulates the zero-order-like rate behavior of the mass-loss process with an apparent activation energy <i>E</i>_a ≈ 70–80 kJ mol^–1. Because of variations in the mechanism of release of the water vapor with changes in the reaction temperature range, the mass-loss behavior is largely dependent on the particle size of the sample and heating conditions. The formation of hollow anhydrous glass is the novel finding of the present study. The mechanism of formation is discussed in terms of complementary interpretations of the morphological changes and kinetic behavior of the thermal dehydration. On further heating, the as-produced anhydrous glass exhibits a glass transition phenomenon at approximately 470 K with an <i>E</i>_a ≈ 550–560 kJ mol^–1, and subsequently crystallizes via the three-dimensional growth of nuclei controlled by diffusion. The crystallization process is characterized by an <i>E</i>_a ≈ 280 kJ mol^–1 and an enthalpy change Δ<i>H</i> = −13.3 kJ mol^–1, resulting in the formation of smaller, rounded particles of crystalline anhydrate

Thermal Dehydration of Magnesium Acetate Tetrahydrate: Formation and in Situ Crystallization of Anhydrous Glass

The kinetics and mechanism of the thermal dehydration of magnesium acetate tetrahydrate were investigated as a typical example of the glass formation process via the thermal decomposition of solids. Formation of an intermediate fluid phase was identified as the characteristic phenomenon responsible for the formation of anhydrous glass. Thermal dehydration from the surface fluid layer regulates the zero-order-like rate behavior of the mass-loss process with an apparent activation energy <i>E</i>_a ≈ 70–80 kJ mol^–1. Because of variations in the mechanism of release of the water vapor with changes in the reaction temperature range, the mass-loss behavior is largely dependent on the particle size of the sample and heating conditions. The formation of hollow anhydrous glass is the novel finding of the present study. The mechanism of formation is discussed in terms of complementary interpretations of the morphological changes and kinetic behavior of the thermal dehydration. On further heating, the as-produced anhydrous glass exhibits a glass transition phenomenon at approximately 470 K with an <i>E</i>_a ≈ 550–560 kJ mol^–1, and subsequently crystallizes via the three-dimensional growth of nuclei controlled by diffusion. The crystallization process is characterized by an <i>E</i>_a ≈ 280 kJ mol^–1 and an enthalpy change Δ<i>H</i> = −13.3 kJ mol^–1, resulting in the formation of smaller, rounded particles of crystalline anhydrate