A comparative lexicogrammatical and logicosemantic systemic functional analysis of two third-grade science curricular units on the topic of "matter" written in Spanish is presented. One of these curricular units, translated from an English textbook, or "mirror text," is used in dual language programs (Spanish-English) in the United States; the other is used in regular elementary science for monolingual Spanish students in some Latin American countries, including Colombia and Venezuela. After a discussion on how standards-aligned textbooks contribute to the deskilling and further disenfranchising of teachers that corresponds to a neoliberal agenda for education, the cross-linguistic analysis reveals that while the mirror text reflected a knower-code structure preoccupied with the here and now and with building interpersonal affiliations, the authentic Spanish text was concerned with building knowledge codes related to global themes seeking to build disciplinary science knowledge. That is, by foregrounding English structure and curricular pacing, the use of translated or mirror texts in dual language programs (in this case translated Spanish versions of English regular textbooks) unintentionally but effectively served as a lexicogrammatical, semantic, and curricular straightjacket not only preventing students and teachers from making potential key meaningful connections between languages but calling into question the possibility of a real language separation.