This paper reports on an innovative and action research project which focused on the use of the dictionary and the prior knowledge of Colombian high school students to improve their reading comprehension of short scientific texts. Data collection instruments included students' work gathered during two workshops, field notes, and a questionnaire. Findings showed that searching in the dictionary and activating prior knowledge seem to facilitate the use of the text to answer reading comprehension questions. Students experienced less difficulty answering questions that required literal information than those that required establishing relationships among elements of the text. They equally valued the prior knowledge of the subject and the use of the dictionary in the resolution of science workshops in English.