Quick-Start Guide: Desmos Classroom for Algebraic Fractions

Today, I've included a quick start guide to finding appropriate activities for helping students visualize algebraic functions using demos. 

Step 1: The Setup (2 Minutes)

1. Go to teacher.desmos.com and sign in (Google Sign-In is usually fastest for 1:1 classrooms).

2. In the search bar, type "Polygraph: Rational Functions" or "Algebraic Fractions." * Pro Tip: Use a pre-made activity for your first time. "Polygraph" is a "Guess Who" style game that forces students to use mathematical vocabulary to describe graphs.

Step 2: Customizing the "Truth Machine" (3 Minutes)

If you want to build your own quick activity:

1. Click "Custom" on the left sidebar and select "New Activity."

2. Add a Graphing Screen.

3. In the expression bar, enter: 

   $$y=\; (x^2-a)/x-$$√a

    

4. Click the button to "Add Slider" for the variable a.

5. Add a Note component next to it asking: "Move the slider. What happens to the graph when 'a' is a perfect square like 4 or 9? Why does the line disappear at a certain point?"

Step 3: Launching the Lesson (1 Minute)

1. Click "Assign" and select "Single Session Code."

2. Project the code on your board. Students go to student.desmos.com and enter the 6-digit code. No student accounts required!

Step 4: The "Dashboard" Phase (During Class)

This is where the magic happens. While students are working, use your Teacher Dashboard:

• Anonymize: Click this to hide student names and replace them with famous mathematicians. This is perfect for projecting a "wrong" answer to discuss as a class without embarrassing anyone.

• Pacing: Use this to "lock" students into screens 1-3 so they don't rush ahead.

• Snapshot: See a great explanation? Take a "Snapshot" of that student's work and project it to the class to spark a discussion.

---

The "Common Denominator" Activity Idea

Ask students to graph $y=\frac{1}{x}+\frac{1}{2}$. Then, ask them to type their "simplified" version in the next line.

• If their second line doesn't perfectly cover the first line, they know their algebraic addition is wrong.

• The visual feedback is instant. They don't need to wait for you to grade it; the graph tells them the truth.

---

Teacher’s Tech Toolkit for 2026

Feature	Why You’ll Love It
Checkboxes	Create "Self-Checking" screens where a "Correct!" message appears only when the fraction is simplified.
Marbleslides	A game where students must change the numbers in a fraction to "catch" stars with a marble—perfect for learning asymptotes.
Card Sort	Have students match an algebraic fraction to its simplified counterpart and its graph