[header] How to celebrate the 100th day of school [title] Decorate your classroom for the occasion. [step] You can use things such as balloons and banners themed towards the milestone. This will show to your students that the 100th day of school is an important milestone and is something that should be celebrated. 
[title] Assign a special homework assignment or project that's due on that day. [step] Having a special homework assignment would be not only fun, but also a great way of celebrating the milestone.