Our staff is built to teach each student individually, to develop the skills they need to thrive in mathematics, and to foster a love of learning.

John Osborne

Owner

Hi, my name is John Osborne, and I’m the Co-Owner of Mathnasium of Franklin. I first discovered Mathnasium as a parent—I enrolled my son, hoping it would help him build confidence in math. What I didn’t expect was how much he loved coming here. The reward system, the caring instructors, and the fun, game-based approach made math feel exciting instead of overwhelming. Seeing that transformation firsthand is what inspired me to become involved in Mathnasium and bring that same experience to more families in our community.

Outside the center, I work in finance. I’m a CFA charterholder with an MBA from the Kellogg School of Management, a BS in Business Administration (with a minor in Mandarin Chinese) from the University of Richmond, and a certificate in Quantitative Data Science in Finance from Stevens Institute of Technology. But the title I’m most proud of is “parent”—and I bring that perspective into every decision we make at Mathnasium.

Fun fact: I lived and worked in Shanghai for four years, and I love sharing stories about it with students who are curious about the world!

Carissa Sirrianna

Assistant Center Director

Hello! I’m Carissa, the Assistant Center Director at Mathnasium Franklin, and I bring over 12 years of experience in education to our center. Throughout my career, I have had the opportunity to serve as a principal while doing what I love most: helping students grow in confidence, learning, and character.

I studied Education Wagner College, which shaped my belief that learning should be engaging, creative, and student centered. I later earned my Master’s in Business Administration from MSOE, where I developed a strong passion for understanding how to best bridge my love for working with children with systems that truly support their success.

One of my favorite parts of working at Mathnasium is watching students realize they are capable of doing math. Seeing that shift from frustration to confidence is what drives my work every day. I believe every child deserves to feel supported, capable, and proud of their progress, and I love partnering with families to help make that happen.

Debbie Franke

Lead instructor

Debby is our longest-serving instructor at Mathnasium of Franklin, and she brings a wealth of teaching experience, patience, and warmth to every session. She spent eight years teaching in both Milwaukee Public Schools and Germantown, and later tutored students at MSOE—giving her a deep understanding of how children learn and what helps them thrive in math.

Families love Debby for her steady, encouraging approach. She knows how to meet students right where they are, build their confidence, and celebrate every step forward. Her experience across different ages and learning styles makes her an invaluable part of our team and a trusted mentor for our students.

Fun facts: Debby plays fantasy football with her children and grandchildren, loves building Legos, and enjoys crocheting and gardening in her free time.

Hannah Carroll

Lead Instructor

Hannah has been an instructor at Mathnasium of Franklin for nearly three years, and we’re thrilled to have her back in the center during her break from the University of Wisconsin–Madison, where she’s studying Actuarial Science. Her strong math background, combined with her friendly and upbeat personality, makes her a natural fit for helping students grow their confidence and skills.

A Franklin native, Hannah has always had a special way of connecting with kids—whether she’s guiding them through a tricky concept or helping run our family events. Families appreciate her patience, warmth, and ability to make learning feel both supportive and fun.

Fun fact: In high school, Hannah was a standout athlete—in 2024, she earned the No. 16 seed in the Division 1 state tennis tournament in doubles. She and her partner won two matches before falling to the eventual state champions!

Ella Biesterfeld

Instructor

Ella is an 18-year-old instructor who brings a wonderful blend of patience, kindness, and positive energy to Mathnasium of Franklin. She currently attends Wisconsin Lutheran High School and plans to study psychology—a perfect fit for someone who naturally understands how to encourage students, ease their frustrations, and help them feel confident in their learning.

Ella connects especially well with younger students and those who may feel anxious about math. Her warm personality, steady approach, and genuine care help students feel comfortable and supported from the moment they sit down with her.

Fun facts: Ella’s favorite color is green ;-) 

Mari

Instructor

Mari is a senior in high school who brings curiosity, patience, and a genuine love for learning to Mathnasium of Franklin. She plans to study astrophysics after graduation, and her passion for science shines through in the way she explains concepts and helps students see the “big picture” behind the math they’re learning.

Mari has a calm, encouraging style that helps students feel comfortable asking questions and working through challenges. Families appreciate how she makes math feel approachable and even exciting, especially for students who benefit from seeing how math connects to the real world.

Fun fact: Mari is fascinated by space and hopes to study the stars, galaxies, and the physics that govern our universe!

Grace Solie

Instructor

Grace is a 17-year-old instructor at Mathnasium of Franklin who brings focus, enthusiasm, and a strong work ethic to every session. She attends Wisconsin Lutheran High School and will be continuing her education at Bryant & Stratton, where she plans to study business and play college softball. Her drive and determination make her a wonderful role model for our students.

Grace is especially great at helping students set goals, stay motivated, and keep a positive attitude—even when the math gets challenging. Families appreciate her encouraging style and her ability to make learning feel both productive and fun.

Fun fact: Grace will be playing college softball at Bryant & Stratton!

Our Mathnasium Mission

Teach children math so they understand it, master it, and love it. Math can change their lives, and they can change the world.

Quote Quote
What I love about Mathnasium is the ability to teach problem-solving skills and make math make sense, while also making a student smile.
Amber W., Mathnasium Instructor

Schedule Your Math Skills Assessment Today

Student using math cubes to solve fractions
Student working with a math tutor at a local math learning center

Want to join the Mathnasium team?

Are you interested in changing lives through math? We're looking for outstanding individuals with a high level of commitment who are passionate about teaching math. Find out if there's a Mathnasium position that's just right for you!

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