Lesson on Volume of Prisms with 3D CAD

A teaching experiment involving three and a half days of 75-minute lessons was conducted for consolidating student learning of the volume of composite solids. The teaching experiment took the form of an open-ended class project, which objective was to, “Design a keychain and have it printed in 3D; consider the time and cost of printing your project.”
On the first day of the project, the students reviewed how to calculate the volume of prisms which was learned prior to the project, and they were introduced the project objective and given time to design their keychains.
As the project name, “3D Keychain Project,” implies, the students were going to make keychains; the mention of “volume” was intentionally avoided in the introduction. The need for calculating volume was later introduced as a real-life application when the teacher suggested that, “due to the time and cost for 3D printing”, the students’ designs must satisfy two measurement constraints: (1) they needed to work within a 50mm x 50mm workspace and (2) the volume of the entire 3D print must not exceed 2500mm3. Before the students began designing in the computer lab, the teacher demonstrated some basic functions of an online 3D CAD environment, Tinkercad (www.tinkercad.com), which included: resizing, rotating, changing views and adding “holes” to various geometrical objects.
On the second and third day of the project, the students continued to work on their designs. The teacher walked around the computer lab to provide technical assistance and advice about the appropriateness of their designs, drawing particular attention on potential printing issues and the measurement constraints imposed on the project. The students also began to work on the written component of the project: “show your calculation of the volume of their designs clearly” and “write a 100-word reflection about your designing process, challenges, and why you enjoyed or did not enjoy doing this project.
On the fourth day, the students did not work on the projects, but the teacher used the first half of the lesson to demonstrate printing several students’ keychains with a 3D printer. The students gathered around a 3D printer to see a keychain printed, while the teacher explained the technology behind 3D printing. The project was due in two school days after the fourth day.
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