Each group needs:

• spring or inexpensive bungee cord with open hooks on each end
• 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 (specifically the LEGO MINDSTORMS EV3 brick with ultrasonic sensor and LEGO parts will be used from the Core Set)
• 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
• computer, loaded with EV3 1.2.1 software
• 1 piece of cardboard, ~6 x 6 inches, or stiff disposable plate, to use as a platform on the bottom end of the spring/bungee cord
• lab stand with attached clamp, or rod parallel to floor
• It's Spring Time Worksheet, one per student

Alternative: LEGO MINDSTORMS NXT Set:

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
• computer loaded with the NXT 2.1 software

To share with the entire class:

• variety of weights that can be hung from the springs/bungee cords