This paper discusses the importance of critical literacy as cross curricular tool-and-result in the teaching learning activity. Based on the Socio-Cultural-Historical Activity Theory (Vygotsky, 1934; Leontiev, 1977), it discusses a teacher continuous education intervention program aimed at the teaching-learning of different subject areas mediated by different genres (Bakhtin, 1953). Teachers' tasks, which really simultaneously develop critical understanding and an engagement with area contents in a non-segmented format, are analyzed and seem to indicate a view of literacy as tool-and-result in students' transformational actions.