Everyone knows everyone else's name, and has a basic idea of who everyone is, which household they belong to, that sort of thing. They may or may not have been stuck in the same place at the same time before for any number of reasons, but it's all been very superficial up to now, as it generally is between young children who don't live in the same house or get forced to play together every day.
By 'brisk', I mean upper 50s for temperature, so everyone is wrapped up against chill, but not nearly so much as in the dead of winter.
Any question, just ask. Off we go, wild blue yonder and all of that.