Intended for grades K-2, this science unit on coastal ecosystems aids teachers in helping students to: (1) identify marine organisms; (2) learn their basic characteristics; and (3) understand the web of interdependence among organisms of the same habitat. The teacher's guide is divided into four sections. The first section gives background information about ecosystems. The second section provides detailed directions on how to collect specific marine plants and animals and includes an application for a permit to collect organisms. The third section explains how to set up and maintain a salt water aquarium, and provides a feeding schedule and list of supply houses, as well as a supplementary booklet for student use. The last section identifies various considerations related to conducting field trips. These include, among others, site selection, scheduling, permission slips, emergency information, clothing, parent volunteers, and equipment. It then outlines specific information for four field trips, including pre- and post-trip activities, investigation procedures, and discussion questions. Student work booklets for each of the trips (pier and jetty, sandy beach, mud flat, and salt marsh) contain pictures of organisms they will collect and questions to answer. (DC)