Product designer Il Gu Cha had you in mind when he created his Trace of Time clock. Write your appointments on the clock's whiteboard face; the hour hand has an integrated eraser that sweeps them away so you can start the next day with a fresh clean slate. This is a "why didn't we think of that" that we could easily see as a DIY. Draw little pictures of various activities on the board to help teach your children the time.
[image: Il Gu Cha, via his website]