Feeding sheep

This is Rosie...and this is Robin. Rosie and Robin are twins.
They grew together in mummy's tummy, close to each other.
Now Rosie and Robin are nearly 3, and they are growing.
They often play together and sometimes they fight.
And mummy's tummy is flat again.

It's Sunday morning. Mummy and daddy are still fast asleep in bed, but Rosie is wide-awake and sitting up straight on her own little bed, looking at a book.
The door opens and a sleepy-faced Robin wanders in. "Hi sis," he yawns. "What are you doing?"
"Shall we build a tent?" she laughs suddenly.
"I suppose so," says Robin slowly, scratching his head.
Rosie pulls an old sheet from her cupboard and throws it over her table.
"Look, this is a sheepfold. And you're a sheep," she explains.
"A sheep?" grumbles Robin. "Who wants to be a sheep? I thought we were building a tent anyway?"