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Friday Fave for January 11

The Friday Fave is working to stave off the mid-winter blues by thinking about delight.

At Desmos, one of our core values is Design for delight. So when we built Penny Circle, we made the pennies bounce off each other, and we made them non-identical.

An animation shows pennies being dragged into a circle. They bump into each other as though they were real pennies.

We made a robot celebrate your mathematical victories in Adding Whole Numbers

An animation shows playing cards being dragged onto two different mats on a table, with the goal of getting the sum of the cards to be the same on both mats. 7 and 6 go on one mat; 8, 2, and 3 go on the other. The robot scans the cards and throws up its arms to celebrate the student's success.

And we made Marbleslides, where you can launch your marbles into the air and through the stars.

An animation shows marbles being launched on a graph; they drop, roll along several graphed lines, through stars that serve as targets, and then down off the bottom of the screen

Of course, we don’t delude ourselves that the electronic world is the primary source of delight in classrooms. We understand and celebrate that there is delight in a clever new student solution, in persistence paying off, and in just connecting to each other as human beings in a shared community. But isn’t it lovely when electronic math lessons bring a spark of delight too?

Delight. This week’s Friday Fave. Find it in lots of places at, including these activities:

Adding Whole Numbers

Marbleslides: Lines

Coin Capture

Transformation Golf: Rigid Motion

Friday Fave for December 21

This week—in this holiday season—the Fave turns its attention to the amazing community of teachers using Desmos tools to support students in creative ways. Click through on each of these posts for great ideas, resources, and links.

In this lesson plan in the form of a blog post, Jenn Vadnais uses Desmos as an instructional tool to help students understand percents and proportions.

The other day a teacher asked me to create a lesson that had elements of a Number Talk involving percents. Her students had recently been discussing proportional reasoning and the constant of proportionality. Knowing this, I decided to combine percents and proportional reasoning with Desmos. Here’s the resulting lesson.

On his blog, Paul Jorgens combines several Desmos tools to support classroom conversations that help students develop mathematical vocabulary with increasing depth and sophistication.

If we are going to develop vocabulary through experiences, we need to build in those activities into our lessons. We try to utilize our “fire up” time to open the class.

Julie Reulbach writes about how she has her students create Desmos art. She supports their learning and project organization by having them complete their art inside a Desmos activity.

Having them do the project through an Activity Builder helped me manage all of their graphs so I could easily view them and access them for help. By using an Activity Builder, I was also able to include the instructions for the projects and helpful tips for them…I had them print out their Desmos Art, and I made a huge collage of it on my wall in the back of the room.

Supporting students with tools, language, and art—this week’s Friday Fave.

Note: The Fave is taking a couple weeks off, and will see you again in the new year. All the best to you, your colleagues, students, and loved ones until then.

Friday Fave for December 14

This week’s Friday Fave requires a little help from your friends. System of Two Linear Equations begins by asking a simple question: Is it possible for two numbers to have a difference of 8, but a sum of 1?

We’re not asking for examples at this point, nor are we expecting you to have techniques ready at hand. We’re just asking for your instincts, and in a sufficiently large class of algebra students we expect some yeses, several nos, and quite a few maybes. Discuss.

Next up, we’ll get specific. Think of two numbers with a difference of 8 and give us the larger one. We’ll guess the second one, plot them both as an ordered pair and ask you to think about what the collection of everyone’s points will look like.

You see what we did there? We created a social experience by connecting you with your friends to discuss some informal ideas, and then we made those informal ideas more formal one step at a time. Pretty soon, you’re writing equations for lines and noticing that their intersection is a number pair whose difference is 8 and whose sum is 1.

More constraints and opportunities to think, share, collaborate, and discuss follow. An informal question—Is it possible?—introduces an invitation to develop some important algebraic techniques.

That’s what makes System of Two Linear Equations this week’s Friday Fave, and while you’re thinking of systems of equations (and inequalities!) here are a few more activities to play with.

Playing Catch Up

Polygraph: Systems of Linear Inequalities

Racing Dots