Exploring Scale Factor

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My fifth grade students explored scale factor and dilations this week.  This was their last week of school and it was a great topic to study as they head off to middle school next year.  Some of the geometry that they’ll see in middle school involves this specific topic. The class started early in the week with a brief Kahoot! on similar figures and enlargements as well as reductions.  This was a bit challenging as some of the shapes were rotating and students had to identify a particular side.  After discussing words like dilation, scale, and factor, I gave students a multi-day project.  This project actually stems from one of Allison’s Tweets that I read earlier in the week.

At first glance the image in her Tweet made me laugh.  My second thought was … wait… this might work in my classroom. You know how a Tweet can spark additional ideas?  Yes.  That happened here.  I asked Allison about the project and she provided additional details about the pre-image.  So I put together a direction sheet and rubric.  I decided to have students use a 5 cm x 7 cm grid.  The class then discussed how enlarging the image would change the horizontal and vertical dimensions.  I decided to not have them reduce images since the pre-image was already so small to begin with.  We did discuss how me might need a magnifying class though.

Students went through their Math Magazine.  They looked for an image inside the magazine that they found interesting.  Some students found something immediately, while others took some time.  Students then traced over the 5 cm by 7cm card, used a straightedge to create grid lines, and then finally cut out the sheet.  Students then pick their scale factor page.  Just about everyone picked the 15 cm by 21 cm grid.

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Note to self:  In the future I need to have students randomly  (maybe with dice) pick a different scale factor page.  

Students were then off to work in creating the image.  Some students asked questions about whether they needed to enlarge everything on the image.  Yes.  Interesting … some students thought it was just the picture that was enlarged and not the text.  Everything in the gird was increased by the same factor.  Once that was covered students made steady gains for the next 20 minutes.  They started with pencil and then shaded in the rest with color.  Students were proud of what they accomplished during the first session and many wanted to finish them up at home.

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Students finished up their scale factor projects on Friday.  Since it was the last day of school I sent them home.  I gave each student a survey (this might be another post) before leaving and it was interesting that many commented about how they enjoyed learning about scale factor and ending the unit with a project like this.  Maybe it’s because it was the first thing in their mind, but I thought this type of project was worth the time and will help students moving forward as they discuss similar figures next year.

I’d like to find more time over the summer to create more memorable math activities similar to this. Kids can then hold onto these experiences past the last day of school and look back on them as they make connections next school year.

Author: Matt Coaty

I've taught elementary students for the past 14 years. I enjoy reading educational research and learning from my PLN. Words on this blog are my own.

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