The best experimental setup to investigate the connection between kinetic energy and temperature would be:
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 observe the diffusion of food coloring in two different temperatures, which directly relates to the kinetic energy of the water molecules. The higher temperature (40ºC) should demonstrate faster diffusion compared to the lower temperature (10ºC), illustrating the connection between kinetic energy and temperature.