Sociological thinking predated the formalization of Sociology as a discipline. It actually started out more in the realm of Philosophy. There are examples of sociological thinking found in Philosophy as far back as the works of Plato, and the works of Islamic thinkers such as Ibn Khaldun, who is argued to be the first Sociologist.
Continuing in its philosophic roots, Auguste Comte who is regarded as "The Father of Sociology", used the term "social physics" to discuss sociology, but it was Emile Durkheim who formalized sociology as a discipline unto itself. Durkheim published the first official sociological work, Rules of the Sociologic Method and set up a Sociology department at the University of Bordeaux. He then went on to establish the journal L'Annee Sociologique.
However, the US took a slightly different stance on Sociology. A Sociology course was taught for the first time at Yale in 1875, preferring the Comte thought process over the Durkheimian thought process. Departments of Sociology were soon established in universities in the US, especially in the Midwest. George Herbert Mead and Charles Cooley were strong influences who gave rise to Social Psychology in the US.
I think it's likely that your teacher will expect certain information from your particular book or lectures. Please be sure to consult your book or notes to see if you have any information -- what I give might not be exactly what your teacher expects.
Sociology as an academic discipline dates to the early 1800s. It grew up in European countries (such as Great Britain, France, and Germany) that had been most strongly affected by the Industrial Revolution.
In such countries, the society was changing so fast that people started to be interested in studying the effects of the changes. As they studied the effects of societal changes on people, the field of sociology was born.
Important early names in the field of sociology were Auguste Comte (often seen as the founder of the discipline), Herbert Spencer, Emile Durkheim, Max Weber, and even Karl Marx.