Saturday, November 05, 2011

Magic Hand and Transversals...

We started talking about 2 lines cut by a transversal this week in geometry. I had fun with the "magic hand" statement, and it seemed to work with my students. I held up my hand at the appropriate moment and asked them what it was ..... "a magic hand!", and then I placed it over the "4th line" that I had drawn.

I also mentioned that the two lines could be like sandwich slices and the transversal is the toothpick that goes through the sandwich. So when I had them identify types of angle pairs, I could keep saying, "who's the bread? who's the toothpick?". That seemed to help them be successful once the "magic hand" removed an extra line.


  1. I love the sandwich with a toothpick analogy. Totally trying that on Monday.

  2. It's ALL about the food :)

  3. Magic Hand? Just some goofy term I came up with when I lifted my hand .... then I showed them how to use theirs to cover up the "extra" line(s) that may make it more difficult to identify the "bread slices and toothpick".

  4. Anonymous7:37 AM

    I love the quote about the "white-out opportunity."

    Very catchy, and better than my speel about not being God, and only God doesn't make mistakes.

  5. Excellent article, it’s pleasure to read your blog ?

  6. I draw dotted lines between the two parallel lines so that it makes a box. Then we identify angles by telling if they are inside the box or outside (interior or exterior) and then if they are on the same side or alternate sides of the transversal.

    We also have a song about angles to the tune of the ABC song:

    Alternate interiors make a “Z”
    And they are equal as can be
    Same side interiors make a “C”
    But they are supplementary
    If you want to correspond,
    “F’s” will be your equal ones.

    We spend a lot of time just tracing the different angles so that the students can 'see' the Z,C, and F. Also, whichever line the students trace over twice is always the transversal. It's become one of my favorite lessons.