One of my favorite lessons to do the first day of school is to have my kids do a classroom scavenger hunt. The questions are pretty straight forward. I ask about the number of chairs, desks, bookshelves, etc. Then I throw in this question, "How many numbers do you see in this classroom?" It is my absolute favorite question because the past two times that I have done this, my kids have figured out that there are thousands of numbers in the classroom. They start to see the number line on the wall, the clock, the hundreds chart, rulers, the calendar, book box numbers, clip chart numbers, etc. Some even noticed the nameplates on each desk that also include a ruler, hundreds chart, and number line.
My favorite memory of last year was when one of my kids stood at the front of the room, arms stretched out, and shouted, "THIS WHOLE ROOM IS MADE OF NUMBERS!" It seems like a silly thing for the kids to do but you really get to see your kids' ability to observe and think outside of the box. This little discovery leads into my explanation that math is EVERYWHERE and it is so important for them to realize the real world connections with math.
To close the lesson, I read The Math Curse by Jon Scieszka. It is a book that appeals to students from 2nd grade to college. My college professor actually read it to us during math methods. Some of it is way over my kids' heads but they still get the overall meaning that you can make anything into a math problem.