Questioning to ascertain prior knowledge is a very popular practice, but there is a danger when posing questions to the whole group that we only get a sense of what a few students know rather than everyone.
Teacher as teller is a short talk that provides the background information to the reading or viewing. It ensures that all students approach the reading or viewing with the necessary background information.
It is much easier to understand what we read when we have some knowledge of the topic. This is, of course, something of a Catch 22 as background knowledge is acquired by reading.