1: Ask questions. Ask why. Ask how. Ask whether your answer is right. Ask whether it makes sense. Ask what assumptions you have made, and whether an alternate set of assumptions might be warranted. Ask what if. Ask what if not.
2: Play. See what happens if you carry out the computation you have in mind, even if you are not sure it’s the right one. See what happens if you do it the other way around. Try to think like someone else would think. Tweak and see what happens.
3: Argue. Say why you think you are right. Say why you might be wrong. Try to understand how someone else sees things, and say why you think their perspective may be valid. Do not accept what others say is so, but listen carefully to it so that you can decide whether it is.
So go ahead and do it–ask, play, and argue all throughout break. The more we practice being mathematicians, the better we can teach other mathematicians.
(Also, hopefully you’re having an easier and easier time figuring out what it looks like for students to ask, play, and argue in your own classrooms. But if you want one more example, check out the “estimation wall.”)