Geometry – Day 58 – Area II & Area Applications

Why We’re Here:

  1. We’re going to learn/review the area of trapezoids and kites.
  2. More to the point, we’re going to get started with applications of area.
  3. We’re also going to assess (14) Translations.


  1. Concept Quiz #17

The Breakdown

  1. Opener + Review (15 minutes)
  2. Area Notes (15 minutes)
  3. Area Classwork (25 minutes)
  4. Break (5 minutes)
  5. Show and Tell (1.5 minutes)
  6. Application Notes (10 minutes)
  7. Application Classwork (20 minutes)
  8. Assessment (10 minutes)
  9. Homework: pg. 423 // #1 – 3


Slide Deck

  1. dreamt
  2. Make sure they know that the sides aren’t the same as the height.
  3. Have them draw a kite and remember what the diagonals are. Do you see the rectangle?
  4. Working backwards from area. Good rigor.
  5. Show them how to draw a rectangular solid from parallelograms.

Notes & Revisions:

  1. None
I'm Dan and this is my blog. I'm a former high school math teacher and current head of teaching at Desmos. He / him. More here.


  1. Both in opener and the quiz in b) you say translation when I am fairly certain that you mean transformation. Since you’ve given this test already, it’d be interesting to know how many students realized that b) in fact was not a translation.

  2. Transformations, according to Keypress, include translations, rotations, and reflections. “Transformations” and “translations” have been used perhaps too-interchangeably in my slides, but both are valid. Thanks for pointing them out, in any case. Gotta watch my P’s and Q’s around you, E.

  3. Hmm, I agree that transformations and translations are both valid names, but not for the same thing. All translations are transformations, but not all transformations are translations. As you pointed out above, isometries (rigid transformations as you called them) consist of translations, reflections and rotations. The one in b) on the quiz is a reflection about the y-axis.