This lecture discusses the calculation of the end-to-end distance in polymer theory, focusing on the algebraic relation between the end-to-end distance and the system's dimension. The instructor explains the probability distribution of the end-to-end distance, emphasizing the isotropy assumption and the mathematical methods used to compute it. The lecture delves into the concept of the Kratky-Porod model and the introduction of correlations in polymer chains. It concludes with a detailed analysis of rescaling the model and its implications for exploring the mechanical properties of biomacromolecules.