Friday, February 13, 2009

Why Are There Green Beans in an Area Project?

My 6 weeks of teaching little brilliant, hormonal, over dramatic, hilarious, 7th graders has ended. I assigned 6 Homework Violations, 2 Detentions, and made 3 kids cry. I'd say it was productive. And really, one of the kids cried because she was sad I was leaving. I was startled and didn't really know what to say. Another kid came to me crying because he got a detention from another teacher who was going to give him one anyway, but had heard that he had argued with me earlier in the day. In all fairness then, I wasn't the one to make him cry. He was the obnoxiously gifted kid who had argued that I didn't understand how to find the area of his shape, a simple octagon. He's a sweet kid and he understood why I graded him harshly after I showed him some of the other kids' work. The third kid burst into tears when I gave him a detention, but after that we were cool. In fact he's the one who put the green beans in the area project.
What am I talking about?

Well, about 3 weeks ago after the students had taken a test, I decided to try an experiment that I had learned about in my Differentiated Instruction class (my favorite class so far). I had the students write down 3 things they were proud of in math class, 3 specific things they were going to work on over the next two weeks, and 3 suggestions they had for making their learning experience better. While the entire 3rd period class felt their learning experience would be better if I threw candy at them and didn't assign any homework, they had some really great ideas. One of those ideas was to have a bright and colorful room.

So I searched online and found this website. Under Chapter 9.1 is an area poster project in Microsoft Publisher. I printed it off with a rubric. Basically, I asked the students to create a complicated shape that could be broken down into smaller shapes that we already know how to find the area for. The shape had to be colorful, complicated, take more than half the size of the poster, and the problem had to be stated in words. Then on a separate sheet of paper the student had to find the area of their shape, neatly showing all their work, and state in words how they found the area. For an additional 5 bonus points they could find the perimeter.

Kids are creative.

And some kids are overachievers.

Naming the shape seemed to cause some problems.
I thought the dumpster was a hilarious illustration of how one girl felt about the project.
And perhaps I may have worn my purple sweater a few times too many...
On my last day, I hung the area posters around the room. Now, the children are back with their regular teacher in a room full of colorful posters.

But what are the green beans? Well, the students were having a hard time understanding that just because the length of the side of the trapezoid is given doesn't mean that that number is used to find area. If you'll remember the area of the trapezoid is found by ½·h·(a+b) where a and b are the bases (the parallel lines) and h is the height (indicated by either being perpendicular to the bases or by a dotted line).
So that side length kept confusing the kids because they felt that if there was a number it should be used. I asked them if they were baking cookies and they had sugar, flour, and butter, what would they do with the can of green beans? They'd leave them in the pantry. The term green beans caught on and it worked to help them figure out area.

Ironically, I love green beans.


  1. Your teaching gig sounds like it was so much fun! I love the projects and the green beans story is absolutely hilarious! Thanks for sharing that :)

  2. I love the chicken. It's awesome. Also, there's something about how, if you're the one asking the questions, you can ask any question you want: "My favorite animal is a chicken, so find the area of this chicken." I love it. I'm totally walking into my class next Monday and saying, "I like perpendicular lines that go through the point (2,3). Draw me a pair."

  3. I loved all youur students drawings. A wonderful project. I think you are an exceptional teacher.

  4. Thanks Gretel, Sara, and Mom!


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