College-educated mothers spend about 300 more hours a year in intensive childcare than mothers with only a high school diploma, yet they enjoy it less. So what's prompting them to spend so much time with their kids? Ariel Kalil of the University of Chicago's Harris School of Public Policy talks about her research on the parenting time gap. All parents say that childcare is emotionally rewarding, so how can we reduce the gap in how they spend their time?