The main purpose of this study is to investigate the effects of three instructional methods on students' technological literacy (TL) and argumentation ability. Participants were 285 seventh grade Israeli boys and girls (12-13-year-old) who studied in 18 technology classes in four junior high schools. The three teaching methods were: (a) teaching technology by exposing students to structured argumentation (SA); (b) teaching technology by encouraging students to explain their reasoning in an unstructured way (UA), without explicit guidance regarding ''what is a good argument'' and ''how to construct it''; (c) teaching technology in a ''traditional'' way, with no emphasis on argumentation (NA). Results indicate that the SA group significantly outperformed the other two groups regarding knowledge of technology, but no significant differences were found between the three groups on knowledge about technology. The SA group also outperformed the other two groups in argumentation. (Contains 4 tables.)