Jan-Markus Schwindt studied physics and mathematics in Heidelberg and Cambridge. He obtained his PhD in 2004 at the Institute of Theoretical Physics in Heidelberg. Subsequently, he spent four years doing research and teaching as a postdoc at the Universities of Mainz and Heidelberg. The focus of his research was on Cosmology and Quantum Gravity. During this time, he often acted as a tutor. Now, he brought his teaching experience into this book.