No more plopping preschoolers in front of videos to “zone out.” With the emergence of touchscreen tablets and e-readers, screen time has become interactive—and thus less guilt-inducing for parents who need a short break. Every purposeful swipe of our children’s fingers seems to offer a reassuring signal that their minds are at work, contemplating what to do next.

Teacher wars are raging across the nation. One side blasts the "bad" teachers, waving around student test-score data and demanding accountability. On the other side are teachers: Defensive, closing the doors to their classrooms — and to the promise of improving their practice.

How do we halt the teacher-bashing, as President Obama urged in his State of the Union address, and still improve the quality of teaching? The answer is to radically change the evaluation conversation. A focus on watching teachers work — on how they actually interact with students — is long overdue.

I used to be a teacher: I wanted to excite children about learning and help shape the minds of the next generation. But like nearly 50 percent of teachers, I left the classroom before my fifth year. And while a higher salary would have been nice, it would not have kept me in the classroom.

Before an audience of voters in Yeadon, Pa., on Tuesday, President Obama announced major changes to the Head Start program, which provides preschool access for children from low-income families, and scolded Congress for not doing more for education.