There really is only one scenario where an educator can tell a parent and child to explore the school. The child, parent and teacher all need to be in the school.
Often what happens is that the school invites the child and parent for a play date at the school. During this time, the educator encourages the child to interact with the other children and explore. This is an important process for the child and the educator, because during this time the educator observes the child to see the child's level of development and more important to see if this child would be a good addition to the school.
However, before the play date, it is always good for the educator to let the parent and child know what to expect.