Are you about to start a unit that you know students find difficult?  By starting off with an over-arching question you give students both a lens, through which to evaluate the new information, and a scale that helps them evaluate the importance of each new piece of information.

An over-arching question is a question that you would hope a student could answer at the end of the unit.  It's not a problem to be solved, or a technique to be used, but instead a question you may ask another math teacher about a topic.  By posing such a question to students at the beginning, and then expecting them to answer it by the end of the unit, it puts students in a new role as learners.

Visit: https://thebeardedmathman.com/podcast/E15 for the show notes and the resources mentioned in the podcast episode.