# Gear Ratios Subject Area: Technology, Engineering, Math Learning Objectives: Students will be able to create a drivetrain and calculate the gear ratio. Materials Needed: One computer, one Micro or Micro+ 3D printer, and one 250ft PLA 3D Ink filament spool per 2-5 students. Brief Description: Students will print a platform, a crank, and a variety of gears. The gears are each labeled with their diameter. The Students can create a unique drivetrain and calculate the gear ratio. To Prepare: Students will need a computer that has the M3D software on it. We recommend one printer per every 2-5 students. The Micro or Micro+ 3D printer will need to be plugged into both the wall and the computer. Each printer will need to have a 250ft spool of PLA feeding into the external port. A spool holder is also recommended. If you need assistance with any of the above please see our guides at support.printm3d.com. Lesson Plan: 1\. Students will go online to: and download the gear ratio models.\ 2\. Students will open the M3D Software on a computer, upload the models, and print: 2 of each of the 4 gear sizes, 8 pegs, a crank, and the gear box board. \ 3\. Once the models have printed, students should create a drivetrain by putting the gears onto the gear box. \ 4\. After they have their drivetrain, students should measure the RPM of the last gear, the torque of the system, and the gear ratio.