ELI5: Explain Like I'm 5

Thermal diffusivity

Thermal diffusivity is a measure of how well a material can spread heat. It tells us how long it takes for a material to heat up when something warm is placed on it. Think of it like a race between heat and cold - if heat can travel through a material quickly, then it will win the race and everything will warm up. If it can't travel quickly, then it will take a while for the material to warm up.