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Mathnasium 10543 4S Commons Drive, #175, San Diego CA 92127 (858) 312-8888

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It's always sunny in San Diego!

Our Team

Our specially trained math instructors will teach your child how to understand math in an individual setting; our unique approach enables us to explain concepts really well and lend a helping hand to every student. Our tutors foster a caring, encouraging environment that helps kids thrive and learn! Read below to learn more about our talented team:

Youngkun, Center Director

4 Year Mathnasium Veteran

Youngkun is customer service driven and has a passion for teaching math.  The desire to help make "math make sense to kids" is what brought to Mathnasium in the first place. Youngkun offers outstanding consultative advice to educate parents and students on the Mathnasium program and the academic expectations of kids today with Common Core standards. Knowing success breeds success, Youngkun's team will help design a learning plan just right for each student so they can meet their math goals in an efficient manner. You can always schedule a time to meet with Youngkun to discuss your student and their mathematical progress by clicking

Meet Our Family Ownernership Team 

Karen Lossing is the center director/owner of the math learning center Mathnasium of 4S Ranch.

Karen Lossing, Executive Director

Karen earned a Bachelor’s degree in Marketing from Penn State and spent ten years in the business community. After staying at home with her kids, she earned her Texas Teaching certification and went on to teach third and fifth grades and Special Ed for seven years. In addition, she served on the Response to Intervention team and was the district liaison for Math Curriculum and Instruction. Karen completed her Master’s degree in 2010 and, prior to moving from Texas, served three years on her elementary school’s administration team incorporating and facilitating 21st Century learning standards.  

Karen has been a proud franchisee with Mathnasium since 2013 and looks forward to making math make sense to all the kids who learn at Mathnasium. Since opening her first location, Karen has been recognized by Mathnasium as a Top Performing Franchise Owner. Karen received the Exceptional People award in 2016 for her ability to hire and train one of the strongest instructional teams through Mathnasium. Karen has also been awarded in 2016, 2017, 2018, 2019 and 2020 for having Top Performing locations. She currently serves on the Mathnasium Franchise Advisory Committee, which helps guide Mathnasium Headquarters as it makes key decisions about the direction of the company. Often our center has the opportunity to pilot new curriculum or student management systems prior to global launches, allowing us to serve our students in the best way possible.

Steve Lossing, Executive Director 

Steve is the proud co-owner of multiple Mathnasium Learning Centers in Southern California, Arizona and Texas. Steve retired in 2018 from Petco, where he served as the Chief Stores Officer. He also served as the Treasurer and a Board Member of the Petco Foundation, a leading supporter of animal welfare organizations nationally. He now works full-time with his wife, Karen, two children, Libby and Evan and their terrific Mathnasium teams.  

Steve believes Mathnasium not only builds students' math skills, but also helps build their self-confidence. The Mathnasium method of teaching students math, the unique and customized curriculum for each student and the passionate team of instructors ensures that every student succeeds, whether they are catching up, keeping up or getting ahead!

Libby Lossing, Director of Operations

After serving as a seasonal Mathnasium Instructor since 2013, Libby graduated from UCLA in March 2017 and joined our team as the Director of Operations. While she is no stranger to the instruction and tutoring aspects of our center, Libby focuses on the community involvement side of our operations. She has founded Teacher Appreciation Programs in San Diego, California and Phoenix, Arizona with local school districts and news teams. If you have any school events or sponsorship opportunities you would like Mathnasium to be involved in, Libby is your girl! Please feel free to send sponsorship information to and Libby will be in touch!

In addition to her role as Director of Operations, Libby also serves as our Regional Director in Arizona, overseeing the learning centers in the Phoenix area. She is proud to partner with our Center Directors and Instructional Teams to deliver the Mathnasium Method to students across the Valley of the Sun.


Evan Lossing, Director of Human Resources

Evan's professional experience with Mathnasium began in 2013 when his family opened their first math learning center. Evan spent many summers and holiday breaks working as an Instructor. After graduating his bachelors degree in Business Management at Texas Tech, he began working as the Director of Operations for our family enterprise and has now relocated back to our hometown in Dallas, Texas!

Evan is excited to work with our students and continue their progress with math. He, himself, struggled with math when he was in elementary school and with supplemental support was able to not only close his gaps but got into an accelerated math curriculum by the time he entered high school. 

Evan is a stickler for customer service and meeting and exceeding your expectations. He welcomes your recommendations. He looks forward to meeting you and sharing his passion for education with our mathletes.