These exercises are writing mathematical proofs that basic machine learning algorithms behave correctly. They are "pen and paper" not because you are manually

These exercises are writing mathematical proofs that basic machine learning algorithms behave correctly. They are "pen and paper" not because you are manually solving a large equation that a machine would normally solve, but because we don't have automated theorem provers capable of proving interesting machine learning theorems. I would expect a typical 1st year grad student to be using a resource like this. If you don't understand the purpose of proofs, then this resource is not aimed at you.