Geometry – Day 54 – Transformation

Why We’re Here:

  1. We’ll understand the difference between rigid and non-rigid transformations.
  2. We’ll discuss the three kinds of rigid transformations and practice identifying them.


  1. None

The Breakdown

  1. Opener + Review (10 minutes)
  2. Review Second Semester Rules (5 minutes)
  3. Notes & Discussion (20 minutes)
  4. Classwork (20 minutes)


Slide Deck

  1. Fresh Kills Landfall Landfill, NY (Newsday)
  2. The increase of detention from 30 sec. to 1 min. is out of respect. I respect your capacity to learn and retain and, after a semester, you know the rules. You now have to decide whether or not to work within them.
  3. Can anyone now define: rigid transformation?
  4. Now?
  5. Draw a rigid transformation and show a friend. Draw a non-rigid transformation and do the same.
  6. What kind of transformation is this?
  7. What kind of transformation is this?
  8. Rotational? Reflectional? Or both?
  9. Rotational? Reflectional? Or both?
  10. Notes & Revisions:

    • 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. Hi Dan – the file attachments don’t seem to be “working” – either a file permission problem or maybe a different name for the directory or files?

    Looking forward to sharing transformations w/ my 8th graders.


  2. Dan,

    All I can say is wow, looks way impressive. I especially like the picture of the house after a non-rigid transformation.

    Does it count as a constructive critique if I say I think you misspelled Landfill as Landfall? Probably not.


  3. Nah, thanks, Steve. The small details irk me most of all sometimes.

    I swear, the most exciting thing about having a projector is that the distance between my imagination and the reality of my classroom is shrinking exponentially. I would’ve printed out those photos last year. I would’ve printed them out and copied them in b & w to transparencies, fumbled with them, and made my point in the best way possible.

    So much more is possible at so much less cost now, you know?