Monday, January 14, 2013

If Barbie Were as Tall as Me- A Lesson in Proportional Reasoning

This lesson idea isn't new; it's easy to find many versions of it all over the internet. In fact, I was inspired by a post from fellow teacher Fawn Nguyen.  Here's my spin on it.  My students need to review proportional reasoning this year, so I wanted to focus on application since they got the basics of how to cross multiply and solve last year.

I started by collecting some Barbies and Kens.  Thank goodness for generous teachers in my district and our fabulous e-mail network!  I got 5 Barbies and Kens in no time.  I bought one more at Goodwill for $1 and now I have enough for each table in my classroom to have one.  I'll try to pick up a few more when I can find them (clothed) for $1 or so.  :)

Students will work in their table groups of four on this project.  They'll need to select one student in their group to serve as the human reference.  That student's height will be used and their silhouette will be traced on bulletin board paper.

Next, students will carefully measure and record data on Barbie's body measurements.  I selected six data points I'd like them to collect and superimposed them on a coloring page of a Barbie doll.  They'll write proportions to find out how large these body parts would be if Barbie were enlarged to their height.  Then, they need to work as a group to make a scale drawing on chart paper.  I'm planning to have them place their scale drawings next to the silhouettes to show off how unreasonable Barbie is.  I'm also curious to see if this pans out in a similar way with Ken or if he's more reasonably made.  His abs are unusual, that's for sure!
A screenshot of a portion of the diagram students will use. 

The individual portion of the project asks students to write a letter to Mattel explaining their findings and requesting changes in Barbie's physique so that it will be more true to life.

Since it's Monday, I'm posting to made 4 math.

EDIT: There's a follow-up to this post here that contains files you can download.  


  1. I really like your version of this, Kathryn! Mine seems too "involved" and I've been thinking of changing it somehow, so you definitely have helped me re-think mine. Sticking with height alone is a great idea too!

    Thank you for sharing and for the shout-out!

  2. This is amazing! Is there any way you could post the handouts that accompany this activity?

    1. An update is coming shortly and I'll post a PDF for you. Thanks for your comment!

    2. Thank you for your awesome ideas!!

  3. Thank you for sharing your ideas! You are a god-send!

  4. awesome activity! I'm going to use this for My Bridging to Algebra 2 class because these kids need the foundations. Follow my blog a I'll be posting stuff for Bridging from time to time that might be useful to you!