“Daddy,” eight-year-old Ellen said. “Would you please drive me to Tracy’s house?” “One minute,” her father said, barely looking up from his handheld device. “I just have to send this text.” Ellen sat down to read a book. She didn’t mean to read the whole book while sitting there, but she had the time—because her dad didn’t send one text, he sent, and received, dozens. Ellen put the book down. She again asked: “Daddy, would you please drive me to Tracy’s house?” “One minute,” her father said, barely looking up from his tablet. “I just have to download these files.” Ellen sat down to read another book. She didn’t mean to read the whole book while sitting there, but she had the time—because her dad didn’t download one file, he downloaded, and sent, dozens. Ellen put the book down. She again asked: “Daddy, would you please drive me to Tracy’s house?” “One minute,” her father said, barely looking up from his laptop. “I just have to send this email.” Ellen sat down to read another book. She