One child is writing various signs all over the play fort a la The Little Rascals and their "he-man woman haters club," one is patiently drawing as many straight lines as will fit in precisely one patio rectangle, one is intently coloring every rock he can find blue and one has dumped the remaining sidewalk chalk out and is generally a hot mess.
There's nothing like some sidewalk chalk to bring siblings together and highlight their differences all at the same time :)