This quantitative and qualitative study explored students' perceptions of a flipped German course and its measurable impact on their critical-thinking skills. The instructional design of the course shifted grammar and vocabulary instruction outside of class so that students in the newly created collaborative in-class space could engage in more communicative tasks and develop their collaborative, problem-solving and critical-thinking skills. The findings indicated that second-language (L2) courses focusing on flipped learning (which differs from the flipped classroom) can have a positive impact on students' perceptions because they create a suitable instructional setting that fosters L2 proficiency and 21st-century skills development, particularly critical thinking.