When I was working on my degree, one of my 2-week field experiences was in a 2nd grade classroom. Every morning, the students completed a "Number of the Day" activity (based on the number of days they had been in school) for morning work. I was completely amazed by the number sense that the students in the class had. I am planning to keep most of the routines of the class I am taking over in tact (because the teacher seems awesome), but this is one thing I am going to try to implement.
Here is my take on the Number of the Day sheet. Click on the picture to download the PDF.