This document provides an overview of Module 1 in a Grade 9 biology unit on living things and their environment. The module focuses on the respiratory and circulatory systems. It includes 3 activities to help students learn about: [1] the key parts of the breathing system and how they work; [2] how the lungs and diaphragm enable breathing; and [3] how the circulatory and respiratory systems work together to transport oxygen and carbon dioxide. The goal is for students to understand how these systems function and to appreciate the importance of maintaining respiratory and cardiovascular health.