This booklet is the first in a series of six sourcebooks produced by Project MAVIS (Materials Adaptations for Visually Impaired Students in the Social Studies). Designed primarily for teachers, the booklet defines visual impairment and its causes, explains how to interpret a student's eye report, and reviews aspects of the overall educational plan of the visually impaired student. Chapter one defines visual impairment in terms of concepts such as legal blindness, "low vision" individuals, and "visually limited" individuals. Chapter two identifies four types of visual impairment: reduction in visual acuity (ability to distinguish fine points in a form), restriction of the visual field (due to blind spots or tunnel vision, for example), deficiency in color vision, and problems related to use of vision (i.e., visual motor ability and visual perception). Chapter three discusses seven causes of visual impairment: cataracts, glaucoma, retinal disorders, macular disorders, retrolental fibroplasia, nystagmus, and optic-nerve atrophy. Chapter four explains how the teacher can interpret a child's eye report prepared by an optometrist or opthalmologist. A sample form used by the National Society for the Prevention of Blindness is shown as an example. Chapter five offers general guidelines for developing an educational plan for visually impaired children, stressing the importance of treating them like normal children while at the same time providing necessary adaptations to accomodate their impairment. The booklet concludes with a glossary of 46 terms and an educator's checklist of observable clues to classroom vision problems. (AV)