revealed the types of connections students made when studying the curriculum and suggested how these connections enabled students to consolidate their understanding as they continued in the chem. Students who used the visualization-enhanced unit formed more connections among concepts than students with typical textbook and lecture-based instruction. Students participating in the visualization-enhanced unit outperformed students receiving typical instruction and further consolidated their understanding on the delayed posttest. Design-based research included a pilot study, a study comparing the visualization-enhanced inquiry unit to typical instruction, and a course-long comparison study featuring a delayed posttest. The inquiry unit supports students to develop connections among mol., observable, and symbolic representations of chem. The visualization-enhanced unit uses research-based guidelines following the knowledge integration framework to help students develop coherent understanding by connecting and refining existing and new ideas. visualizations to improve students' understanding of chem. This paper describes the design and impact of an inquiry-oriented online curriculum that takes advantage of dynamic mol. The user can expand and contract the unit cells from multiple perspectives to help develop a visual picture of an extended crystalline structure. Figure 2C illustrates that the user can use the mouse to rotate and zoom into the interior of the structure to gain additional perspective. Successive expansions allow the user to see the individual unit cells and how they are related to each other. As the expansion slider is adjusted or the keyboard shortcut is pressed, the individual unit cells pull outward from each other by a small step. #VIEWING MULTIPLE UNIT CELLS IN CRYSTALMAKER SOFTWARE#Figure 2 shows a series of screenshots that demonstrate the use of the “expand” feature of the software for a body-centered cubic crystal. The unit cell visualization tool allows users to dynamically relate these two representations with each other. The way that the sliced-apart atoms in unit cell drawings relate to drawings of the extended structure with spherical representations of atoms is not necessarily intuitive. This visualization tool was designed to help students conceptualize unit cells and 3-dimensional lattice structures. If it is represented with eight 1/8th’s, then the meaning of 1/8 of a particle can be ambiguous. #VIEWING MULTIPLE UNIT CELLS IN CRYSTALMAKER FULL#If the unit cell is represented with eight full spheres, the misconception that it contains eight particles arises. In both representations, it is unclear where the particles or parts of the particles come from. For example, a simple cubic unit cell is usually represented as a single cube with either eight spheres or 1/8 of a sphere at each corner. Another challenge in teaching lattice structures is counting the particles in each unit cell. While this technique succeeds in showing the different stacking patterns, it remains limited in effectively showing how the different 3D unit cells arise from each stacking pattern. The simple cubic and body-centered cubic crystals arise from stacking 2D layers with squares while the face-centered cubic and hexagonal close-packed crystals arise from stacking 2D layers with rhombuses. The stacking pattern is aa in simple cubic, abab in body-centered cubic, abcabc in face-centered cubic, and abab in hexagonal close-packed lattices. A commonly used technique in explaining this process is by labeling the different particle layers with the letters “abc” and then listing the stacking pattern according to the types of alternating layers. (9) One of the challenges in explaining the formation of different lattice structures is the stacking pattern of the atoms/ions in the crystal. The long-range arrangement of particles in crystalline structures is often represented by a single unit cell, usually illustrated by a 2D sketch. Crystalline structures are of particular importance due to their interesting electric properties and other physical properties such as shape and hardness. The chemistry of solid state structures and composite materials is covered in most introductory chemistry courses to introduce students to the use of these materials in every-day applications.
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