Both Kuhn and Dear have things to say about medieval science. In the case of Dear, the discussion is part of a brief introduction to the book, so it gives fewer details and I suggest you read Kuhn first.
This assignment includes the first three of the four sections in Kuhn's ch. 4. The first is an introduction that sketches the history of the period, and the other two describe first the relations between science and religion and then the critical attitude towards Aristotle that developed towards the end of the middle ages once his views were fully assimilated. We will focus on Dante's picture of the world in the first of these sections and, from the second, the questioning attitude of Oresme (pronounced "o-rem" with emphasis on the second syllable) and impetus theory.
The main function of Dear's introduction is to present a distinction (marked by the title "Philosophy and Operationalism") that he will continue to draw as he tells the story of the Scientific Revolution in the body of his book. On the one hand are Aristotle and, especially, Aristotle's assumptions and explicit doctrines concerning the nature of science; on other hand, is a view Dear finds in many modern thinkers but associates especially with Francis Bacon (check the biographical glossary at the end of Dear's book, pp. 193-196, for Bacon's dates). You should think about what Dear means by "philosophy" and "operationalism" in this connection. In doing so, be careful to separate his use of these terms here from other uses you may be familiar with; in particular, the most common uses of the term "operationalism" are tied in one way or another to views of science that developed in the 1920s and 1930s and are thus a long way historically from the period Dear has in mind.