The night before the girls go back to school their mom tells them what sex is and reads them a story about a woman in a car crash off a bridge. Good Housekeeping says if you crash your car off a bridge you should rescue your husband from drowning if you can, because if you have a husband you can make more children, whereas if you rescue your child you’ll only ever have that one. Their mom thinks about that a lot. What she would do if they got into a car crash off a bridge. The girls begin to practice how long they can hold their breath when they are alone in their room.