We recast Thom’s classical calculation of the unoriented bordism ring in the language of formal geometry, introducing foundational concepts as we go along, especially: Thom spectra and the Thom isomorphism, formal schemes, and the formal-geometric perspectives on the Steenrod algebra and on the Adams spectral sequence. This chapter is designed primarily with pedagogy in mind, as this calculation introduces all of the main structures used in the rest of the book, restricted to a particularly simple context.