We officially marked our 100th day of school on Monday.  We began celebrating last Wednesday (day 99) with several fun activities.  Children searched the room for 100 numbered tiles, which they matched to their corresponding number on a 100's chart.  Most of these were in plain sight and pretty easy to find, but there are always a couple of elusive tiles.  We did manage to find all of them by the end of the day.  Children also had the option of making a string of 100 beads or a paper chain with 100 links.  On Monday and Tuesday we played a board game to 100, built with 100 blocks and 100 cups, and did a search for tiny pictures of objects arranged in groups of 10 up to 100 (e.g. 30 buttons, 60 legos.)  While celebrating the 100th day is mostly about recognizing a milestone and having fun, I find that emphasis on 100 for a day or two, (or six with snow days), can also deepen children's sense of our number system and how numbers to 100 are composed and written ad groups of 10 and additional ones.