Noticing that the sky is dark and hearing thunder in the distance are examples of observing.

Here's why:

* Observing means using your senses (sight, hearing, touch, smell, taste) to gather information about the world around you.

* Seeing a dark sky and hearing thunder are both using your senses to notice changes in the environment.

These observations could lead to the inference that a storm is approaching, but the observations themselves are simply the act of gathering information through your senses.