The phrase "simple observation" means noticing something in a straightforward and easy way, without overthinking or analyzing it too much. Full definition
Early on, children develop a sense of how relationships are formed and how they are maintained by simple observation of their parents. (personalityresearch.org)
The essentials of financial planning affect our children whether they are learned by simple observation or whether we take the time to teach them these things. (lifeinsurancehub.net)
They had the knowledge from simple observation and record keeping. (religion.blogs.cnn.com)