This learning resource delves into the concept of cosmic expansion and its role in the cooling of the universe. It aims to explain how the stretching of space-time led to significant changes in the state of matter, ultimately resulting in the creation of the Cosmic Microwave Background Radiation (CMBR). The resource includes instructional activities such as a '60-Second Brain Dump' where students reflect on cosmic expansion, visual aids depicting the evolution from a hot singularity to an expanding universe, prediction tasks about temperature changes during expansion, and collaborative discussions that promote critical thinking about how this expansion contributes to cooling. Through various engaging methods, students build their understanding of the fundamental principles of cosmology.