Некие семьи маленькие, а некие большие. Поглядите на рисунки на страницах

Например:

The Greens is a large family. They are: a mother (Mrs Green), a father (Mr Green), an aunt, an uncle, a nephew, a grandmother, a daughter, a son and a little baby.
The Smiths is a big family. They are: a mother (Mrs Smith), a father (Mr Smith), a grandmother, a grandfather, a daughter and two sons.
The Adams is a small family. They are: a wife (Mrs Adams) and a husband (Mr Adams).