A useful household system map shows what you observed, the boundary you chose and a few explained connections. It can help you choose one permitted change and decide what would make you reconsider it.
Systems thinking includes several related approaches. This course mainly uses stocks, flows and feedback from system dynamics, alongside questions about assumptions and boundaries. The optional lessons give more diagram notation and recurring patterns.
The practical test is whether the record helps you investigate your particular problem. Completing the course does not show that your explanation is correct or that you have changed the real situation.