Here's another idea to help you celebrate 100 day. How about 100 beats of rhythm? Have every child in Kindergarten or First grade cut and/or color a beat - whether it is a quarter note, quarter rest or eighth note pair - which might be done by two students. Or you could have your students work together to create 100 measures of rhythms. You will want to start with how many you have in the grade level you are working with and then decide which arrangement will accomplish your goal. What a fun thing to have lining the hallway as far as the eye can see!