Each state requires different criteria for establishing high school credits. Please note this is not an exact guideline but a glimpse into how I used Mystery of History volume 1 for a high school credit.
Linda Hobar goes into great detail on ways to break down the time needed for using Mystery of History for high school credit.
The following list includes the criteria of assignments. The goal is to spend 4 to 5 hours a week on (affiliate link) Mystery of History high school credit.