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Wednesday, March 23, 2011

The Wheat from the Chaff

I am frequently poo-pooing TI's offerings on their website around here, so I thought I'd balance the karma by advertising a pretty decent activity we did today: Midpoint Quadrilaterals.

It has the right amount of intellectual rigor and things for the kids to actually do, and the documents that suggest a progression of inquiry did not require much modification. There are four parts, and for each part I made sure they knew what they were expected to do and look for and write down, gave them time to work, then regrouped and had them share their conclusions and reasoning.

I also inserted a task before proving that the inscribed quadrilateral was a parallelogram (after Page 1.3) to remind them of triangle midsegments which looked like this:

...which if this interests you enough to check it out, I'm sure you can figure out why.


  1. Kate, this looks really nice. I was wondering - do your kids all have their own TI calculators, and do you have this all showing on a smartboard during the lesson?

  2. They are supposed to all have their own, but they don't all have them with them on any given day. So, I check out half a class set (15) from our department office to use as loaners.

    I do have all this showing on a smartboard during the lesson.

  3. I feel like Geogebra would work much better for this activity than TI-calcs.

    I do like the activity, but the nSpire feels clumsy to use in comparison with a full computer, or a smartphone.

  4. Use it any way you like. I often adapt Geogebra and Sketchpad investigations to Nspire. It's just the platform that's easiest in my classes.

  5. Thanks, Kate, I just like to get the big picture. The thing that strikes me most about this is that I have never had this topic on any of my syllabuses (syllabi?), and I wish I did, just so I could use stuff like this. Was this on your course syllabus or an enrichment type of thing?

  6. We don't have a standard that says "know that the midpoints of the sides of a quadrilateral make the vertices of a parallelogram." But I was a little ahead of the game after our quadrilaterals unit, and this had a nice review of special quadilateral properties, used some reasoning and proof, and also reviewed triangle midsegments which we used the next day on trapezoid midsegments.

  7. I agree that this would be very easy to do on geometer sketchpad. I have a class set of ti-83s, so I'm breaking one out now to see how easy this is for my students in middle school.


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