Meet Our Amazing Instructors

Jingqing Chai

Jingqing Chai

Teaches grades 1 to 9

Education: PhD in economics, Stanford University

Professional Experience: Senior economist at International Monetary Fund, Senior advisor at UNICEF New York Headquarters, Math Kangaroo USA curriculum development expert, Founder of Westchester Math Kangaroo League.

Instructor Approach: problem solving with math kangaroo is a self discovery process – students are encouraged to always ask themselves 3 questions: 1) How may I get started and if a particular path didn’t work out, what else might I try? 2) Now that I solved it, is there a better, more elegant way? And 3) How can I apply the insights gained from solving this problem to other related problems including from higher grade levels? For the initial step of this self discovery, I use props and hands-on experiments whenever possible, like having the students cut out and draw on 2D nets using graphing paper to build and manipulate 3D cubes.


Zoya Dimitrova

Teaches grades 1 to 4

Education: Master of Science, Informatics and Mathematical Modeling, Sofia University, Bulgaria
Master of Science, Computer Science, Georgia State University

Professional Experience: Biostatistician at the Centers for Disease Control and Prevention, Math Kangaroo Instructor since 2006, Math Kangaroo State Director

Instructor Approach:  I enjoy the Math Kangaroo problems and have led several math circles for students of different ages.

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Diana Holan

Teaches grades 1 to 6

Education: Master in Education

Professional Experience: Elementary and middle school teacher for 30 years in both private and public schools instructing in an in-person and online format. Math Kangaroo Manager and Math Kangaroo Coach

Instructor Approach: Math is my favorite subject to teach. I like to offer students various methods of approaching a given problem, then help them apply those concepts to real-life situations through detailed, logical, and organized explanations.
I strive to help students achieve their utmost potential because I believe all students have the capability to be successful if they put their minds to it.


Sumit Kohli

Teaches grades 1 to 5

Education: Bachelor of Science in Computer Science & Engineering
Master of Business Administration in Project Management

Professional Experience: Principle architect at T-Mobile, Math tutor for elementary and middle-school students with MATHCOUNTS, Math Olympiad, Code Buster, Fermi, Math League, and Math Kangaroo

Instructor Approach:   I love to raise math awareness in kids, share creative and interactive strategies, and inspire kids to be their best in STEM.


Van Koroleva

Teaches grades 1 to 12

Education: PhD, Applied Mathematics

Professional Experience:Industrial research. Taught applied mathematics and introductory physics courses to hundreds of college students in small group sessions. Developing new courses and teaching grade school students. 

Instructor Approach: I let students discover mathematics by guiding them through the problem solving process. Not only does this approach help them remember mathematical concepts better, but it also helps them become independent learners. I also found that incorporating stories about the history of mathematics and its many applications greatly enhances students’ interest in the subject.


Lucia Liu

Teaches grades 1 to 6

Education: Bachelor of Science, Electrical Engineering
Master of Business Administration

Professional Experience: Math teacher, Vice President, Director of Administration, Office Director, Executive Assistant to CEO, Program Manager, Sales Manager, Marketing Manager

Instructor Approach: I firmly believe that mathematics is the foundation of all subjects. So, for over ten years, I have devoted myself to mathematics education. I am a passionate, hard-working, determined, and highly motivated person who is supportive of others when they need my help or assistance.


Sarah Sagi

Teaches grades 1 to 6

Education: PhD, Biomedical Sciences, UC San Diego

Professional Experience: Teacher/Head Coach of the Deer Canyon Elementary School Math Club

Instructor Approach: As a teacher I try to help students understand new material through the activities they already enjoy. My teaching philosophy is to listen to my students and respect their mind’s thinking patterns. We learn based on our unique experiences.

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Samvel Sahakyan

Teaches grades 1 to 12

Education: Master of Science in Computer Science and Mathematics from the State University of Armenia
Master of Science in Data Science from Cornell University

Professional Experience: Mathematician and inventor in the IT sector. Designs programs for math competitions and Olympiads, such as AMC-8, AMC-10, and more. Math Kangaroo state director.

Instructor Approach: My passion for math came early in life when I won several math Olympiads and competitions, including a national Olympiad. Many of the students I tutor are winners of national and state competitions.

Changhui Xu2

Changhui Xu

Teaches grades 1 to 12

Education: PhD, Material Science and Engineering
Masters of Business Administration

Professional Experience: Founder of the Iowa City Math Kangaroo Center and State Director for Math Kangaroo.

Instructor Approach: I enjoy math and won numerous awards when I was in elementary, junior high, and high school. I also enjoy teaching and interacting with kids. I believe math skills can be trained and want to pass my knowledge to my students.

Ying Yang

Ying Yang

Teaches grades 1 to 6

Education: Master of Engineering
                    Ph.D. Business

Professional Experience:

University professor, founder of the iGrow Club, math club volunteer

Instructor Approach: I enjoy exploring the world of math with curious minds and I am passionate about motivating children to love math. 

Amy Lee2

Amy Lee

Teaches grades 1 to 12

Education: Bachelor in TIME 2000 & Teacher Academy at Queens College, Master in Teachers College at Columbia University

Professional Experience: I have been dedicated to working with young thinkers! I currently teach high school math, am the recipient of the 2013 Early Career, 2018 Master Teacher, and 2022 Master Teacher II Math for America (MfA) Fellowship, and have coached middle school and high school math teams since 2014.

Instructor Approach: My love of mathematics coupled with my education experience drew me to the Math Kangaroo community. Besides teaching and coaching math teams, I love to cook, hike, and run!

Li, Justin

Justin Li

Teaches grades 1 to 12

Education: Pursuing Bachelor’s in Computer Science and Physics at Harvard

Professional Experience: Tutored in many subjects, especially math, for 4 years. Math Kangaroo Competitor Experience: 6x national winner (all with perfect scores), 12x participant

Instructor Approach: As a recent competitor in Math Kangaroo as well as other math competitions, I can highly relate to both the triumphs and struggles of competitive math. I see my role as a catalyst in achieving your student’s full potential through challenging and supporting them. I place a high emphasis on developing your student’s mathematical skills, but ultimately, I hope to inspire my students to love the process of problem solving.

Maya Viswanathan

Maya Viswanathan

Teaches grades 1 to 8

Education: High School Senior (graduating in 2024),
took Math classes at UIUC: Fundamentals of Mathematics, Combinatorics, Graph Theory

Professional Experience: Math Kangaroo online class teaching assistant, creator of MK video solutions, 4x national winner (all with perfect scores), 10x participant, leader of math club

Instructor Approach: I want to share my love of math with other students. I help them arrive at solutions themselves, by  giving hints and encouraging them to try different approaches. Although math is a rigorous subject, I never forget to have fun.

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