Input (grade 12): The hippopotamus is semi-aquatic, inhabiting rivers and lakes where territorial bulls preside over a stretch of river and groups of 5 to 30 females and young.
Output (grade 6): The hippopotamus is semi-aquatic. This means that even though it usually lives on the land, it spends a great amount of time in rivers and lakes where males lead groups of 5 to 30 females and young.