This NOAA computer-based activity is designed to teach students in grades 9-12 how satellite imagery and remote sensing can be used to monitor harmful algal blooms (HABs). This lesson teaches students how to read and interpret satellite images and how to use GIS maps and satellite images to interpret the relationship of HABs and manatee deaths. The activity features a lesson plan and a step-by-step activity containing hyperlinks that connect the student to the relevant images and maps.