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Hinge Questions: Dilations

20 Dec

Students noticed and noted.

1 Dilations 4.gif

I wanted to be sure that they could answer a dilations question based on their observations. I had two questions premade in my set of Quick Polls. Which question would you ask?

In the past, I would have asked both questions without thinking.

I am learning, though, to think more about which questions I ask. If we only have time to ask a few questions, which questions are worth asking?

From slide 34 in Dylan Wiliam’s presentation at the SSAT 18th National Conference (2010) “Innovation that works: research-based strategies that raise achievement”.

3.5 Screen Shot 2016-12-19 at 2.49.57 PM.png

I decided to send the second poll. I decided that if they get that one right, they can both dilate a point about the origin and pay attention to whether they are given the image or pre-image. If I had sent the second poll, I wouldn’t know whether they could both do and undo a dilation.

4 Screenshot 2016-11-11 09.24.27.png

Next we looked at this question.

5 Screenshot 2016-11-15 09.14.34.png

Students worked on paper first.

Then some explored with technology.

6 Dilations 5.gif

What do you want your students to know about the relationships in the diagram?

What question would you ask to see whether they did?

I asked this question to see what my students were thinking.

7 Screenshot 2016-11-15 09.19.05.png

And so the journey to write and ask and share and revise hinge questions continues …

 
3 Comments

Posted by on December 20, 2016 in Coordinate Geometry, Dilations, Geometry

 

Tags: , , , , , ,

3 responses to “Hinge Questions: Dilations

  1. howardat58

    December 20, 2016 at 4:10 pm

    For scale factor 3 I get OA=2.5 as well. Should be green.

     
    • jwilson828

      December 20, 2016 at 4:16 pm

      Yes! I just took the picture before I had marked the correct response. Sorry for the confusion, and thank you for your comment.

       
  2. howardat58

    December 21, 2016 at 8:28 am

    Try this one….

    If two points, A and B, are dilated about the origin by a factor of 3 what is the connection between AB and A’B’ ?

     

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