Here is Gage with his countdown calendar. When preschool was over at the end of May, he thought kindergarten would immediately follow, and he also didn't understand the concept of 3 months. I tried to tell him about 90 days, but that was just too abstract for him to grasp. So I printed out monthly calendars for the summer, so we could cross of each day and keep a countdown to the first day of school. So far, it has been a big hit.
Each night, he loves crossing off the day, and then every few nights, we count how many days are left and write it on the day we just crossed out. He's learning a little about the concept of time passing, but we are also practicing counting past twenty and writing our numbers, which as you can see (maybe), he sometimes writes backwards. I think writing on the wall is messing with his head!