This educational math video provides a clear, step-by-step tutorial on calculating both the total capacity of rectangular containers and the volume of liquid inside them. Through two distinct examples, the video demonstrates the formula for volume (length × width × height) and explains the critical difference between the height of the container itself (capacity) and the height of the liquid level (volume). The content focuses on key geometry and measurement concepts, specifically working with 3D rectangular prisms. It reinforces the relationship between cubic centimeters and milliliters, explicitly teaching that 1 cm³ equals 1 ml. The video also covers metric unit conversions, demonstrating how to convert larger amounts of milliliters into liters and milliliters (e.g., 5,400 cm³ = 5L 400ml). This resource is highly valuable for upper elementary and middle school mathematics classrooms introducing volume. It offers a visual method for distinguishing between the space a container *can* hold versus what it *currently* holds—a common point of confusion for students. The step-by-step calculations shown on screen serve as excellent models for setting out math problems, and the inclusion of unit conversions connects geometry skills with measurement fluency.