**This project can be completed at home or in the classroom.** Humans have baked bread for over 10,000 years. All over the world, different cultures bake their own unique breads – and have for centuries. Yet we know almost nothing about the microbes that truly make a traditional sourdough bread. In this project, you can create your own sourdough starter from scratch,  just by mixing flour and water. Over the course of 10 days, you can take a series of simple measurements to track the growth of your own "microbial zoo". Your measurements will help solve the mystery of bread, by quantifying how different flours contribute to the growth of each "microbial zoo" – and how those microbes contribute to the taste and texture of bread.