Question

Why does a large lake filled with cool water have more thermal energy than much smaller pond filled with warmer water

Answer 1

because there are more particles in the large lake than the smaller pond
let's try to compare the large lake with a bucket full of 50$ and the smaller pond with a small bucket of 50$, which one has more money
of course it's the big one right?
do u understand now

Answer 2

Objects can’t contain heat however they can contain thermal energy. Temperature measures how hot or cold an object is compared to a reference point ( a temperature that you can refer to like a melting point or a freezing point)

The temperature of the object relates to how much kinetic energy it possess. Kinetic energy is the movement of particles in an object. So more particles means more thermal energy. The larger pond will have more volume of water hence it will have more particles in it, therefore, it has more thermal energy