The History of the World Study Guides do not include a midterm or final exam. However, many parents/teachers make a midterm or a final by taking some of the important short answer and ID questions from various chapters that have been covered so far, and adding an essay question. Others create their own essay question covering some overarching theme of the book; for example: "How do rulers use religious belief or ritual to influence their people?"
Homeschooling families tend to need less formal testing: by personal interaction with the student, parents generally have a good idea of what the student is and is not retaining, and what the student has to say about historical events and trends--especially if the parent initiates conversation or assigns a historical topic to a writing assignment for English.
Formal testing is more necessary in a classroom setting where one teacher is evaluating the progress of multiple students and using grades to communicate the evaluation to the student and to the parents.