The following is a great video on creating content for the IB curriculum:
This is a great video on producing lessons for IB Math: IB DP Mathematics: Embed a concept-based approach:
A student that has that conceptual understanding should be able to answer these questions:
What makes for a lesson to have a great conceptual understanding? (content and skills: how to use technology, connect the context to a mathematical topic, …)
Using open ended questions is a great strategy since the early age, as it fosters inquiry techniques, modeling, investigation and honestly not being comfortable with the assessments you have in front of you (resilience). Students can ask whether they need more tools or information, and may search for some of that missing piece.