One day as we sat on the back porch, I asked my two youngest to close their eyes very tightly and just listen. My kindergartener knew instinctively what to do and described what he could hear: helicopter, birds, kids playing, a bumblebee flying past his face. The three-year-old had more trouble focusing (and keeping his eyes closed), so I told him to listen for specific sounds. "Can you hear the car going by? Where do you think that bird is chirping?"
We also tried to be completely silent for one minute. Ha--way harder than it sounds. Did you ever play "The Quiet Game" when you were little? I think it's easier to be still when no one is telling you to be still. Once there's a goal or a requirement, the temptation to talk is just too much. Our silent minute looked more like giggles about to erupt.