Clip 7/7: Standard 4: Model with Mathematics Using Quadrilaterals A

Mathematically proficient students can apply the mathematics they know to solve problems arising in everyday life, society, and the workplace. In early grades, this might be as simple as writing an addition equation to describe a situation... They routinely interpret their mathematical results in the context of the situation and reflect on whether the results make sense...

Cathy Humphreys leads an extended exploration of a proof of the properties of quadrilaterals, helping students learn to investigate, formulate, conjecture, justify, and ultimately prove mathematical theorems. In this clip, Humphreys introduces the task by posing a problem as a real-life investigation in which a kite manufacturer who “only manufactures quadrilateral kites”, and needs to know the properties of convex quadrilaterals that will always result in a given kite shape, saying “how to do the sticks is the issue.” The students work in groups to give prototype advice to this manufacturer, so that any time an order comes in, the manufacturer will always know “what kind of sticks to put in the kit and how they are to be put together.”

See this video in the context of an entire lesson.