This article discusses closed-loop systems, namely Cradle to Cradle and circular economy, in the context of sustainable education. These circular models, at least ideally, promise absolute decoupling of resource consumption from the economy. This article presents student assignments applying these models to Hennes & Mauritz, a clothing retail company, and insect food producer, Protix. While the discussion of circular economy revolves around the economic benefits of closed-loop systems, it rarely addresses posthumanism. Posthumanism is related to postqualitative theory, inspired by Gilles Deleuze and Felix Guattari. Deleuze and Guattari emphasize that nature has become intertwined with technology and culture. In the cases discussed, combining both techno- and organic materials produces ‘monstrous hybrids’. It appears that fully circular solutions are rare as absolute decoupling is limited by thermodynamic (im)possibilities. This realization still has to be developed in environmental education. Within this posthumanist inquiry, the larger lesson from the case studies is the necessity of teaching about degrowth in production, consumption and corporate strategy. In pedagogical terms, this article aims to generate a more critical discussion within the environmental education community about how postqualitative inquiry can provide different and distinct perspectives from qualitative inquiry in the context of the circular economy.