Terracotta is an open-source experiment builder that plugs into a learning management system (LMS) course site. Presently, a researcher can use Terracotta to easily manipulate class assignments for random groups of students, connect experimental treatments to meaningful outcomes, and export deidentified data. Terracotta also makes it easy to collect informed consent in an LMS assignment, and non-consenting students are automatically removed from any data exports. And with support from the Tools Competition, we are excited to build Terracotta Messages – a brand new service in Terracotta that will make it possible to also conduct rigorous research on personalized messages that teachers send to students.