Lisa and Edward love playing in the sand together. They are both four years old and they have played with cars in the sandbox on Sunday for almost a year. Lisa has dug tunnels, and Edward has dug up sand to make buildings with. They have dug for hours every afternoon without getting tired. Every week, Lisa has dug through the sand very carefully so the tunnels do not collapse. Edward has dug into the corner of the sandbox to get the moist sand. That is better for building with, he thinks. Their mothers have taken pictures of them playing in the sandbox to show them how much they like digging.