You are teaching in a three-year-old classroom. What various activities would you use to help the children experience one-to-one correspondence?

You are teaching in a three-year-old classroom. What various activities would you use to help the children experience one-to-one correspondence? Remember the children in the room may not all be at the same stage of development. How would you assess their understanding of the concept? What would you expect to see going on in the classroom, if children are beginning to grasp this concept?