Being trusted to babysit someone’s kid means being handed the most important thing they have. Act like it.

Nothing else gets handed over on those terms. Whatever a parent says casually on the way out, they are leaving the person they care about most with you, and the casualness is mostly nerves being managed. Treating it as a straightforward way to make money misses the size of what was given. The job is attention, not supervision from the sofa.

Put the phone down while they are awake and stay where you can see them. Learn where the first aid things are and who to call before you need either. Text the parent one short update, which costs nothing and is remembered for years.