Learning to write nonfiction text is an important literacy skill for primary level students. This lesson guides students in writing descriptions about their 100th day bottles. Following demonstration lessons, students work at home to identify one hundred objects to collect and describe. They practice descriptive writing by writing clues about their bottles for a guessing game. As a culminating activity, students create a class book that is added to the classroom library. This lesson offers ideas for integrating mathematics and writing, makes connections to families, and engages students in learning. Sample letters, downloadable activity sheets, and additional resources for 100th day celebrations are available at the website. (author/ncl)