The Kingdom of God is a huge subject.
The "Kingdom of God" has been called Jesus' primary topic. "It's coming and it's also here, be part of it." Many of his parables talk about the Kingdom — where it is, how it is, who's in it, how you can be part of it. It's a subject our kids need to know about.
Jesus used dozens of stories, sayings, and teachings to describe some aspect of the Kingdom. From Beatitudes to Parable of the Talents and more, you could spend an entire year of Rotations trying to cover what Jesus said about the Kingdom.