Some cautions: this is a class in the history of the English language and therefore dates--at least approximations--do make a difference. When formulating answers, always consider the significance of the question in the context of the history of the English language and its relevance to that context.
Indo-European
Grimm's Law
Verner's Law
Grammatical Gender
Alfred the Great
Vikings/Old Norse
You should be able to provide an approximate count for the number of Indo-European languages vis à vis the total number of languages spoken today and the relative proportion of speakers of Indo-European languages to non-Indo-European languages. You should be able to provide a summary of those features that differentiate Germanic from Indo-European. You should be able to recognize (given the infinitive, preterite, and past participial forms) Old English weak verbs, strong verbs, and anomalous verbs. You should be able to distinguish Old English phonemes and allophones. You should be able to provide a plausible date for the beginnings of (Old) English and to provide a justification for it.