Embryos are masterful bioengineers, with the ability to build every organ of the body from a single fertilized egg. This process demands astonishing coordination— millions of cells taking on specialized functions in precisely the right locations— yet embryos build healthy organisms with near perfect regularity. This project aims to understand the origins of this reliability: how do embryos prevent, recognize and correct mistakes before they cause birth defects? The work will be broken up into three interconnected parts. First, the investigators will build and experimentally test a new mathematical theory to explain how embryos communicate error-free instructions to their cells. Second, the investigators will develop and deploy a new microscope technology to observe developmental errors with unprecedented depth and accuracy. Finally, the investigators will engage Pittsburgh-area high school students in experiments to determine how embryos compensate for unexpected changes in external conditions. Over the long run, this work aims to discover new principles that enable bioengineers to build replacement tissues with the reliability and precision of an embryo. Additionally, it aims to inspire the next generation of biologists by providing cutting-edge research experience to high school students. Embryos must communicate precise instructions to their cells. Clear communication is no easy feat, however. An unpredictable environment, random mutations and even noisy intracellular