I hope you'll find these calendar squares to be a nice addition to your classroom calendar. They measure 2". I like to print them, cut them out, mount them onto larger cardstock squares and laminate.
In addition to the calendar, I've also used them for math centers in the following ways:
Pick two cards and add or subtract the numbers shown.
Less than / Greater than: Draw two cards, write them down and add the appropriate symbol in the middle (< or >).