What are the three things every map needs in order for someone else to read it? Elizabeth Thompson, a visiting educator with Putnam | Northern Westchester BOCES’s Center for Environmental Education, asked Susan Cohen’s third grade class this question. Students readily named a map’s title, key, and compass rose. "You're ready to make a map," Thompson said. She introduced them to the alidade, an instrument that accurately shrinks the distances between two objects and allows the preparation of a map by direct observation.

Students worked in small groups in the common area between the classrooms. They were quickly absorbed in the collaborative process of holding the alidade still, walking string out to the objects being mapped, counting measurement marks on the string, and noting the objects’ locations on poster board.