The first step in a great lesson is a “Do Now”– a short activity that you have written on the board or that is waiting for students as they enter. It often starts working before you do. While you are greeting students at the door, or finding that stack of copies, or erasing the mark-ups you made to your overhead from the last lesson, students should already be busy, via the Do Now with scholarly work that prepares them to succeed. In fact, students entering your room should never have to ask themselves, “What am I supposed to be doing?” That much should go without saying. The habits of a good classroom should answer, “You should be doing the Do Now, because we always start with the Do Now.”
Hey I have an even better idea. Start the kids working while they're eating their cereal with me! Tweet them a puzzle that their cereal bowls yell at them in the voice of their favorite Disney character from out the tiny speakers in their IOT china.
Because now can be defined arbitrarily. And hesitation and “what am I doing?” have nothing to do with teaching. Or learning. You should always know what you're doing. Otherwise you're a loser. Gotta keep on keeping on!