Do your students recognize a square if the base is oriented horizontally but call it a "diamond" if it is turned 45 degrees? Do they claim that a shape is a triangle because it "looks like" one? Do they say that one object is "bigger" than another without attending more precisely to the attribute they are comparing? What tasks can you offer-what questions can you ask-to determine what they know or don't know-and move them forward in their thinking?...