The kid is sitting at home in the state of a solid because he is not moving much and his activity is all in one place.
Going through the melting point, the child starts to walk to his bus stop in the form of a liquid because he is moving.
Now going through boiling point, kids are running onto the bus in the form of gas because the kids are in fast motion running to the bus.
Going through the freezing point from gas to liquid to solid, all the kids are in the form of a solid now because they are sitting on the bus and having very little movement and all of their movement is in place,
Going through the melting point the kids are now going from a solid to a liquid in which they now are moving off of the bus into the school.
Going through the freezing point the kids are now sitting in class with little motion in the form of a solid.