The best experimental setup for investigating the connection between kinetic energy and temperature is:
Placing one drop of food coloring in a cup with 50 mL of water at 10ºC; placing one drop of food coloring in a second cup with 50 mL of water at 40ºC.
This setup allows the student to compare how the temperature difference (10ºC vs. 40ºC) affects the diffusion of food coloring, which is related to the kinetic energy of the water molecules. Higher temperatures will typically result in faster diffusion due to increased kinetic energy among the water molecules.