Day 94: Conditions for Parallelograms

Geometry is right in the middle of exploring quadrilaterals. The last few days have been a lot of fun. Today, students explored what it takes for a quadrilateral to be a parallelogram. I found a great worksheet over at Math Teacher Mambo, that you can find here. There were some great discussions on the student’s end of things, on in particular involved fingers as manipulatives.

I was looking for some practice for students and came across this


The second sentence bothers me; students can take a lot more away from a problem in discovering that there is more than one correct answer, instead of just being told so. Always add more later, don’t give it all away in the beginning. The wording above holds students hands and screams: “HEY, LOOK, THERE IS MORE THAN ONE ANSWER” and “Reach one solution, then call it a day”

There is more power and value in rewording this to:

What additional information do you need to conclude the figure is a parallelogram?

Then add a nice extension later on…

Rectangle? Rhombus? Square?


One thought on “Day 94: Conditions for Parallelograms

  1. I think “take information/instructions away” is one of the best teacher insights. With that one tool, suddenly a huge library of mediocre activities are salvaged and become triggers for real discussion and mathematical exploration.

    if you are working on quadrilaterals now, have you seen Chris Danielson’s post on hexagons?
    Start and these two. I’m not sure I got all of them, maybe there is one more.


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