Shading My Linear Art Projects

First I want to thank those who have tried my Linear Art Project in their classrooms.  I think this gives students a great experience with linear equations and how the slope/intercept impacts them.  I have had a lot of questions on how I shade my projects (thank you Missy and Jessica), and now that Hunting, NCTM and Thanksgiving is done I’m back on task to answer this.

So let’s say I created this awesome pumpkin on Desmos:

pump1First, the challenge of actually graphing the pumpkin is something to celebrate!  (YES!!) Then the question arises, Mr. A- How do I color it?  The first thing I have to alert you to (and that I need to remember to ask Ely about) is the color limitations.  Currently in Desmos you have the following color choices:

pump2This can make things tricky.  Trying to get a specific color becomes a problem.  Since pumpkins are Orange however, it works out well for me.

To get things to shade, you have to use an inequality.  For the above example lets look at his right eye.  I want to shade it, so instead of an equation I create an inequality. I first find the equation I want to change:

pump3

Now, I want to shade above it, so I want to use the “greater than or equal to” modifier.

pump4You now notice that I have black covering a large chunk of my awesome pumpkin picture.  that’s because I need to provide a lower AND upper limit to my shading.  I need to find the equations of the other two lines that create the top of my pumpkin’s right eye.

pump5

Now I need to make a compound inequality where the upper limit is -2x-3 and the lower limit is -3 for the interval {-1,0}.

pump6

 

Now you will notice a few weird things, first half of the line for the bottom of my eye disappeared.  That is because I modified my interval to be the same as the interval for the line that created for the top of my eye.  Second, you will notice a heavy line now creating the border of my eye for that interval- showing you what part of the graph your inequality is shading.  Third, you will notice that you have it shaded!  YES!!

To complete the eye, I have to change the equation for the top left part of the eye into a compound inequality:
pump7You have shaded in the right eye.  Going backwards in this fashion, you can complete the shading of your whole picture.  This can get frustrating to students and many will lose the equation of their original lines because they are trying to modify them.  One thing that helped me here is that I had students create their inequalities in a new line under the original equation.  This gave the picture a bolder outline of the shapes and allowed students to always have their original work.

This is a link to my BSU Beaver logo I created using compound inequalities.  It took a while, but I really liked the outcome- and students do as well!

https://www.desmos.com/calculator/guvl1g2mvf

 

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