The measure of average kinetic energy of a group of molecules is temperature.

Here's why:

* Kinetic energy is the energy of motion. The faster a molecule moves, the higher its kinetic energy.

* Temperature is a measure of the average kinetic energy of the molecules within a substance.

* The higher the temperature, the faster the molecules move, and the higher their average kinetic energy.

It's important to note that temperature is a macroscopic property, meaning it describes the behavior of a large number of molecules. Individual molecules can have varying kinetic energies, but temperature represents the average for the whole system.