For the teacher demonstration:

• LEGO MINDSTORMS EV3 robot, such as the EV3 Core Set (5003400) at https://education.lego.com/en-us/products/lego-mindstorms-education-ev3-core-set/5003400#lego-mindstorms-education-ev3
• LEGO MINDSTORMS Education EV3 Software 1.2.1, free online, you have to register a LEGO account first; at https://www.lego.com/en-us/mindstorms/downloads/download-software
• 12 binder clips (see Figure 2)
• 30 hex nuts, such as the 5/16-inch zinc-plated coarse-threaded hex nuts at Home Depot
• string, 4 feet (1.2 m) length
• computer
• stopwatch

Each group* needs:

• LEGO MINDSTORMS EV3 robot, such as the EV3 Core Set (5003400) at https://education.lego.com/en-us/products/lego-mindstorms-education-ev3-core-set/5003400#lego-mindstorms-education-ev3
• string, 4 feet (1.2 m) length
• 1 binder clip
• 4 hex nuts
• computer with MATLAB by MathWorks; if Matlab is not available in your classroom/school, download a free trial at https://www.mathworks.com/programs/trials/trial_request.html?prodcode=ML&s_iid=main_trial_ML_tb and the RWTH - MINDSTORMS EV3 Toolbox for MATLAB at https://www.mathworks.com/matlabcentral/fileexchange/18646-rwth-mindstorms-nxt-toolbox
• stopwatch
• Pre-Quiz, one per student
• Building Guide for Modified Gear Set, one per group
• Engineering Challenge Worksheet, one per group
• Post-Quiz, one per student

*Note: Ideally, build one setup for demonstration purposes and provide each group with its own EV3 Core Set (additional software packs do not need to be purchased) to build their own experimental setups. Multiple setups facilitate the activity, but if not available, conduct the activity with only one setup, which requires the EV3 Core Set and software.

Note: This activity can also be conducted with the older (and no longer sold) LEGO MINDSTORMS NXT set instead of EV3; see below for those supplies:

• LEGO MINDSTORMS NXT robot, such as the NXT Base Set 
• LEGO MINDSTORMS Education NXT Software 2.1
• computer, loaded with NXT 2.1 software