I must say, this calendar is working out pretty well. I know it takes time for the kids to grasp these concepts, but they're really getting into it. The actual calendar is dry erase so it allows for us to quickly add things to the calendar and notes at the bottom. Just yesterday we talked about when field trip money was due and added it to the calendar and then we put a note at the bottom about when our field trip would be in the upcoming month. The coloring coding of the hundreds, tens, and ones has also been very helpful.
My calendar was inspired by my desire to make it more meaningful to my students and this picture on Pinterest:
Then, a few weeks ago, I saw this picture on The Inspired Apple. I really like how interactive it is so I'm thinking about making this on poster board and using it as a math tub that the kids will complete with their group.