Let them keep a calendar.
This picture was taken on the first of this month, when Norah's calendar was still blank, before she'd labeled any of her activities with symbols or crossed off any days with the red marker she's designated for that purpose.
I purchased this in January because I was sick and tired of answering Norah's whinny questions of "How many days till we go to swim lessons?" or "What day is it?" or "What day do we go to church?" This way, Norah would have to go find out for herself. And, it's working really well. If she ever goes to her calendar, but still has trouble with "What does T-u-e-s. stand for?!" that is where I chime in with an explanation.
She loves keeping her own calendar. It makes her feel empowered, I guess. She started drawing X's at the end each day, right before bed, but now she is writing letters instead. The letters will, eventually, spell her name. "N for Monday, O for Tuesday..." she explains, looking up into the sky and listing the letters on her fingers. "Whatever she wants," I think. It's her calendar.
Right now she is supposed to be practicing days of the week, months of the years, etc. anyway. And, I love hearing her flip the pages and say to herself "...March, April, May..." or seeing her point to the boxes "...Wednesday, Thursday, Friday, Saturday! Mom! We're going to the park on Saturday!"
So, consider letting your little ones keep a calendar of their own. For my little one, it is going along way towards teaching her the things she needs to know anyway.