Develop and enact norms and appropriate language for how the classroom community should interact around these topics. Make those public, practice them, and reflect on them. Anticipate and plan for challenging conversations.

It's critical to have a safe space where students feel comfortable in posing their questions and trying out their thinking with one another and you. Intentionally build relationships during the project, and bring the group together for community circles.

Keep in mind that the students should be talking more than you. Lean on student-centered practices that position the students as the primary sense-makers. Examples might be jigsaw, concept attainment, or text-based seminar.

And don't let overly prescriptive PBL muck up good student inquiry. If students are already posing good questions, don't stop that down with some formal Know/Need to Know process. Be willing to adapt to the natural directions that the student inquiry takes you!