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Day 112: Area & Perimeter

Today was partially lost to more (optional for our school) standardized testing, so the Unit 7 Assessment had to be moved to Monday. I generally hate Monday assessments, but in order to get Unit 8 fit in before spring break, sacrifices must be made.

The only topic left in Unit 7 is area & perimeter of quadrilaterals so I used Geogebra to show how we can find shortcuts to solve for the area of various shapes. I don't bother with formulas for perimeter - as long as students understand what perimeter is (and how to use the Pythagorean Theorem to solve for diagonal distances), I assume they'll be able to figure it out.

In general, our theme for finding area is based around the idea of making a rectangle either from the quadrilateral directly (parallelogram), or making the rectangle *around *the shape and noticing that it's area is double the shape's area.

In my head, understanding how to determine area is more useful than memorizing a bunch of area formulas, but students are unfamiliar with a general approach and generally feel more comfortable with the formulas. Except, most students cannot reliably use a formula as a result of very weak algebra skills. Or, they lack the ability to differentiate horizontal/vertical distances on a graph from diagonal lengths. Or they have no idea how to identify a base and a height.
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