For my middle children who have had exposure to calendar concepts, I put together a little weekly schedule for reviewing calendar concepts. It alternates between the Hijri and Gregorian calendars. It provides a quick little way to regularly review both calendars.
https://www.dropbox.com/s/fuzurow8sli5e1l/calendar-review-daily-table-isgreg.pdf (updated link 11/25/2012)
Talibiddeen Jr. Companion Blog 