A study examined the effects of prior knowledge on the reading comprehension of disadvantaged first-grade students from an inner-city school in northern Utah. A thematic approach using trade books, field experiences, Language Experience Activities, and student journals was used to increase background knowledge of the at-risk first graders who were studied. The entire class participated in the field experiences and observations; four at-risk students from the group were selected for pre-trip and post-trip interviews. Qualitative research using observation, interviews, and journals was conducted in the classroom. Results showed deeper and richer prior knowledge and understanding in the post-trip interviews. Data gathered suggest that using field experiences and related activities can be a powerful way to extend prior knowledge, build schema, and make up experiential deficits in at-risk first-grade students. (Contains 72 references; appended are examples of various journal, observational, and question forms used in the study.) (Author/CR)