Using iSpartan To Support a Student-Centered Activity on Alkane Conformations

problem-, case-, and team-based approaches. Each promotes meaningful course engagement, with students being actively involved and controlling their learning process. 5 The activity described here capitalizes on the hallmarks of student-centered instruction by allowing students to advance their understanding of alkane conformations by investigating relevant trends that are traditionally obtained through a lecture or course reading.

In organic chemistry, student-centered instruction is enhanced by the use of dynamic models that help students create accurate mental images of molecular phenomena and derive meaning from structural data. [6][7][8][9][10][11][12][13][14] Learning concepts related to alkane conformations, in particular, can be complicated by the simultaneous need to demonstrate visual literacy and representational competency. [11][12][15][16] Viewing three-dimensional models may reduce the cognitive load imposed on students' memories when approaching problems that require an understanding of such structural information. 11,[17][18] Therefore, tools that allow for the visualization and manipulation of structures, such as iSpartan, can aid a student's mastery of concepts like alkane conformations.

Uses for iPads in the chemistry curriculum continue to expand to support paperless classrooms, collaborative learning, and visual and computational activities. [18][19][20][21][22][23][24] The touch-screen technology coupled with platforms for viewing three-dimensional structures is a beneficial tool for teaching visual concepts. 25 The use of iSpartan [26][27] has emerged in the literature within the past five years, although the full and textbook versions of Spartan have been widely used for pedagogical purposes. [28][29][30][31][32][33] The activity described herein gives students the opportunity to manipulate dynamic models in a threedimensional space using the iSpartan app.

Inc.; Irvine, CA). The structures were distributed to students through a shared drive (Dropbox, Inc.; San Francisco, CA).

The iSpartan activity was completed in four parts, over the course of three class periods (Table 1).

Instructions and follow-up questions for each part were organized into four worksheets (Supporting Information). Students received a summary of expected learning objectives (Table 1). Specific concepts related to alkane conformations were introduced through the completion of the activity and related discussions. Students initially attempted each worksheet alone before discussing the solutions in groups of 4 -5 students. The instructor was available to explain how to interpret the iPad structures and calculate properties. The instructor also monitored group discussion and answered questions when needed. A class discussion was facilitated by the instructor to confirm solutions and ensure 65 comprehension of the information presented in each worksheet. During the discussion, group members presented their answers and provided an explanation that was affirmed or corrected by the instructor. Before the activity, students completed an online reading assignment and quiz that addressed interpreting energy diagrams (see Supporting Information). In Part 1, students learned to import structures into iSpartan and manipulate the three-dimensional representations generated in the app.

The instructor demonstrated how to align the iSpartan structure to thee-dimensional representations (saw-horse, wedge-dash, and Newman projections). Although students had the option of drawing the molecule in iSpartan, students were observed using gestures 25,34 and mnemonic techniques (see supplemental information) to translate between three-dimensional representations. In addition, students had access to handheld models which some used to confirm what was observed on the iPad screen.

For part 2, students used iSpartan to measure the dihedral angle between the hydrogen atoms designating the eclipse, gauche, and anti substituents of ethane (Figure 1). Students combined the 80 measurements with the information from the reading assignment to discuss the relationship between structural features and calculated properties. Students noted that the terms corresponded to the relative location of the hydrogens on the axis of rotation.

Part 3 allowed students to consider the differences between the conformations of ethane and butane. The angles between designated substituents and the energy of each conformation were provided in the worksheet. Students were able to visualize the relative size of the methane substituent versus the hydrogen substituent using the models included on the worksheet. Therefore, this portion of the activity did not require the use of iSpartan and could be completed outside of class. It is noted that manipulating the three-dimensional representation of butane and calculating the properties in the app would be helpful, but did not occur in this case due to the amount of time allotted for the discussion of this topic. Students were, however, able to manipulate the butane molecule within the app while completing the subsequent worksheet. Students discussed their worksheet responses during the following in-class discussion. Substituent size and interactions were reemphasized in Part 4. The space-filling model was used to illustrate substituent size and steric interactions (Figure 2). one class period. the degree to which technology is used for this purpose should be increased. In addition, 63% of respondents agreed with the statement that technology had enhanced their learning. Finally, 57% of respondents felt that iSpartan had enhanced the professor's instruction of the material. Fourteen percent of respondents favored in-class discussion, which during this period consisted primarily of the iSpartan activities. The data suggest that students found the activity and the use of technology in 135 general to be instrumental in their ability to understand and master the topic. In addition, the responses suggest that the iSpartan app should be used to develop similar activities for other structure-based concepts (e.g., mechanisms). In light of this, it is believed that students having access to the app outside of class could potentially increase the benefit of the technology and improve students' understanding of properties that can be correlated to the structure of a molecule.