Faculty

Lesly attended the University of California, Davis where she earned a BS in Biological Sciences. She is pursuing her Masters of Science in Nursing with a family nurse practitioner specialization. Lesly has spent the last five years working in both the medical and educational fields. She previously worked as a 7th grade math teacher at Prospect Sierra Middle School. In her spare time, she enjoys exploring, spending time with her family, and serving at her local church.

Lesly Ayala, B.S., Science Department Head

Marta has a B.A. in English from Lewis and Clark College in Oregon, with a minor in Classical Studies. She continued studying Classical Studies at the graduate level, but realized that her passion was in education, and spent several years tutoring and teaching English, history, and math to middle and high school students before joining the Tilden family in 2017. She has a teaching credential in English, and believes that all students are capable of becoming strong readers and writers with the right support and guidance in finding the stories they love. She also enjoys delving into the depths of history to find the reasons behind any given event, and does her best to share the most interesting historical details with her students (and anyone else who will listen). She teaches English, history, social sciences, and Latin. In her spare time, she likes reading, drawing, and tabletop gaming.

Marta Blanchard, B.A.

Miguel previously worked as a Math Empowerment Teacher for the nonprofit organization Making Waves Education Program located in Richmond, CA. Here he supported low income students in a one-to-one setting. Miguel found Tilden’s Prep model to be nearly identical to that of his previous job. Intrigued with this similarity, he started teaching at Tilden Prep in June, 2013. Miguel holds a B.S. in Mechanical Engineering from UC Berkeley and teaches a variety of courses including math through Calculus BC, chemistry, physics, and computer science. In his spare time he works as an online math curriculum developer and webmaster for "MathFortress.com", an educational website that he created for the purpose of expanding his reach to a greater audience via unique video tutorials for various mathematical disciplines.

Miguel Chan, B.S.

Coral del Mar is a native of Puerto Rico. With the island being a gateway to the Caribbean and popular tourist destination, at a young age Coral recognized that language and cultural knowledge were keys to unlocking insights into other worlds, which inspired her journey with American Sign Language and Deaf Culture. Coral graduated from the University of Puerto Rico, Carolina with a Bachelor's degree in Cultural Tourism, extensively studying ASL. In her students, she seeks to ignite the passion she has found for ASL and other languages and cultures around the world and around us every day.

Coral del Mar Ramos, B.A.

Keiko was born and raised in Tokyo. She started tutoring middle and high school students while in college, and following graduation, taught English and later became certified as a Japanese language teacher in Japan. She started teaching Japanese at Tilden in 2007, and has enjoyed teaching from Japanese 1 through the AP level to many students. She also enjoys watching Japanese anime, drama, and movies. In her spare time, Keiko enjoys flower arranging, and is a licensed teacher of Ikebana (Japanese flower arrangement).

Keiko Endo

Bjorn Fox has an undergraduate degree in Mechanical Engineering from San Francisco State University and a Master's Degree in Management from Cal State East Bay. Bjorn has one year of experience working as a substitute teacher in small to medium sized classrooms and experience as a tutor. He joined the Tilden team as a math and science teacher in 2022. 

Bjorn Fox, M.A.

Gabriel is a recent graduate of UC Davis with a B.S. in Mathematics. Before completing his degree, he tutored privately in Solano and Marin Counties for four years and at Solano Community College for another three. Gabriel greatly enjoys getting to know his students. He believes that everyone has unique ways of learning, understanding concepts, and solving problems. He works to develop the individual skills of his students and learns from the strengths of each one.

Gabriel Fredericks, B.S.

Melody has taught independent, parochial, public, charter, and Christian school students. Her experience inside and outside of the classroom includes K-12 consulting and volunteer projects. When she is not learning from or teaching students, you will find Melody reading, writing, gardening, or planning her next travel adventures! Also, an avid sports fan, Melody and her husband enjoy collegiate football and the collegiate women's and men's basketball seasons.

Melody Fuller, B.S., M.P.A, M.F.A

Joshua Harris grew up in Wyoming and received his B.A. from Brown University. After graduation, he worked at a Native American boarding school in South Dakota and served in the US Peace Corps in Mali, West Africa. Josh then earned his J.D. from UC Davis and practiced environmental law for ten years before attending and teaching creative writing and fiction classes at SFSU, where he earned an M.A. in English and an M.F.A. in Creative Writing. In 2019, he published his first novel, Unorthodoxy.

Joshua Harris, M.A., M.F.A., J.D., Humanities Department Head

Roslyn encourages creative and critical thinking and promotes mindful living. She has a B.A. in Philosophy, a B.F.A. in Jewelry/Metal Arts, and an M.A. in Humanities and Leadership. Her background includes graphic design and various roles in education. She has taught philosophy, humanities, and English at several colleges and universities. Her artistic interests include photography, drawing, painting, and jewelry making.

Roslyn Johnson, M.A.

Born in Los Angeles and raised in Brooklyn, Zoran earned a Bachelor of Science in Chemistry at Lafayette College and a Doctor of Philosophy in Chemistry at the University of California, Berkeley. In addition to teaching Chemistry at UC Berkeley Extension and privately tutoring high school and college students taking chemistry, physics, and math classes, he has held a variety of software positions, including in developer and tester roles. His first love is chess, and Zoran is proud to have played third board on the Stuyvesant High School national champion chess team his senior year. Interest in puzzles, other games, math, sciences, and software followed. He enjoys the "Aha!" moment when teaching as well as when learning.

Zoran Kurtovic, Ph.D., Math Department Head

Amy, originally from the Bay Area, received her Bachelor's degree in Literature and Creative Writing from UC Santa Cruz. Her area of expertise is poetry, and she enjoys writing, reading, and teaching it. Amy is passionate about connecting with students through literature and writing as a form of expression. She has experience working with many age groups, personalities, and communities.  She is also a big fan of horror movies, collage-based art, Jewish literature, and alternative rap music.

Amy Lewites, B.A.

Xuannga “Sonia” Mahini is a graduate of the University of California, Berkeley, with a BA degree in Biochemistry and a Master of Public Health (MPH) degree. Prior to joining Tilden Prep in 2021, she worked for various national and international environmental consulting firms and the Electric Power Research Institute. In her role as Regional Director, Manager, or Principal, she has trained numerous chemists, engineers, environmental professionals, and toxicologists to perform comprehensive risk assessments for the protection of public health and the environment. She enjoys tutoring her son and his friends in all subjects, as their needs arise. She is currently living in Berkeley with her family and enjoys cooking, gardening, home construction, designing jewelry, sewing, and taking care of her aging neighbors.

Sonia Mahini, M.P.H.

Aicha is a mom to two beautiful, creative young adults. She worked on art projects with preschoolers to high school seniors, actively helped organize, photograph performances, field trips, camps, concerts, art projects, fundraisers, cook outs, drama productions. Aicha was  a volunteer trip leader for people with disabilities and under-resourced youth with ETC's winter ski program. She speaks several languages and has lived on four continents; Aicha enjoys most people and appreciates quirkiness and originality in others. She is passionate about photography, and specializes in triptychs. Her work is collected by art collectors, clients and friends all over the planet. Aicha has B.A. in architecture with a minor in photography and sculpture from Pratt Institute, studied photography at Camera Obscura, political science at the University of Tel Aviv, and enjoyed woodworking classes at Laney College. She loves to live, cook, eat, hike, kayak, travel, learn new things, build and be with her family and friends. Aicha joined Tilden teaching art and photography in 2022. 

Aicha Nystrom, B.A., Art Department Head

Corey is a San Diego native with a degree in mathematics/computer science from UCSD. He has a seven-year track record as a private tutor helping students achieve their academic goals and working professionals transition to a career in programming. Recognizing the challenges in STEM, he is motivated to be a supportive teacher, simplifying complex concepts, with the goal of empowering students in the pursuit of their greatest academic dreams. His philosophy as a teacher is to make learning enjoyable by helping students see the real world applications of math and gain a deeper appreciation for numbers. Outside of teaching, Corey’s favorite hobbies are going to the beach, playing guitar, and hiking.

Corey Skinner, B.A.

Carla grew up in the scenic Napa Valley, where her passion for science blossomed. She earned her bachelor’s degree in chemistry in 2021, followed by a master’s in chemistry with a focus on education in 2024. Carla began her career as a lab technician at a local winery before transitioning into teaching. For the past two years, she has taught environmental science and honors chemistry at the high school level.

Carla Sanchez Torres, M.S.

Ana Tafur is a Spanish and Latin American literature teacher  She graduated from the University of California, Davis, and earned her Ph.D. She has taught Spanish and Latin American literature to students of all ages for the past fifteen years. In her spare time, Ana enjoys cooking, reading poetry books, watching documentaries, learning Portuguese and walking in nature with her husband and her mini Schnauzer, Pandita.

Ana Tafur, Ph. D.

Dylan received his B.S in Mathematics from the University of Chicago. He previously taught at Head-Royce School in Oakland, and is invested in and inspired by seeing students go from bewildered to enlightened. In his free time, he plays ultimate frisbee and pickleball.

Dylan Thiermann, B.S.

Rick earned his B.A. in English Literature from St. Mary’s College and Masters in Teaching from the University of San Francisco.  Rick brings over 18 years of high school teaching experience to Tilden.  The best advice regarding teaching he ever received is the simple mantra, ”I am here to help.”  Rick lives in San Leandro with his wife and two dogs.  Together they also share two wonderful daughters (Go Slugs! Go Gauchos!). In his spare time he enjoys live music (often at high volumes). 

Rick Teixeira, M.A.

Dr Kirsten Tranter grew up in Sydney, Australia and has lived in the Bay Area for ten years. She has taught creative writing, academic writing and literary studies at institutions around the world including the University of California, Berkeley; the University of Copenhagen; the University of Sydney; and Rutgers University, where she completed a PhD in English. She is a published author of fiction, non-fiction and journalism including three novels and short fiction. Dr Tranter taught English for three years at French American from 2021-2024, including grades 9 through 12 and IB English. She lives in Berkeley with her black cat Merlin, affectionately known as "Sauron's Little Helper."

Kirsten Tranter, Ph.D.

Camila is a passionate educator, healer, and storyteller. As a lover of all things math and science, she received her BS in Bioengineering at UC Riverside, then went on to receive her MS in Biomedical Engineering from Cal Poly San Luis Obispo. After working for Abbott specializing in implantable cardiac pacemakers and defibrillators in the Sacramento region for 3 years, she made the switch to filmmaking in 2018. She received her Directing certificate from UCLA, and is the owner of Cammotion Pictures, a production company dedicated to telling the stories of the underrepresented. In December 2023, she moved back to the Bay Area where she grew up to be closer to family, and is happy to be teaching the subjects she loves to the next generation. She is currently in her 2nd masters program studying Counseling Psychology with concentration in Marriage & Family Therapy at USF, and hopes to continue telling healing stories that make others feel seen.

Camila Villanueva, M.S.

Iliana brings her passion for visual storytelling to the classroom, drawing from her diverse background in art, photography, and metal sculpture. She earned her bachelor's degree from the University of California, Santa Cruz, where she honed her artistic skills and developed a deep appreciation for creative expression. With over eight years of professional experience in photography, Iliana has worked across various fields, including portraiture, real estate, and landscape photography. Her hands-on experience and artistic vision inspire students to explore new perspectives and techniques, while pursuing their own creative journeys. When she's not behind the camera, Iliana enjoys sharing her love for yoga through her practice and teaching. She also loves experimenting in the kitchen with new recipes and spending time outdoors, especially hiking the scenic trails of Tilden Regional Park. She is excited to bring her multifaceted background and enthusiasm for the arts to the Tilden school community, encouraging students to discover and develop their unique creative voices.

Iliana Arias-Carillo, B.A.

Originally from Ethiopia, Fassil came to the U.S. after finishing high school and is now a naturalized U.S. citizen.  He holds a Bachelor's degree in Mathematics from the University of Chicago, with a minor in Statistics.   He has also done graduate studies in mathematics at Cornell University and holds a Master's degree in Computer Science from Cornell.   Fassil has worked extensively in the financial services industry in New York in various capacities as an analyst, software developer, and  manager.   He loves mathematics, enjoys teaching, and has taught for over ten years.  Fassil has a talent for strategy board games such as checkers, chess, shogi and go and is rated amateur 3-dan in shogi.  Among the things he currently likes to do in his spare time is watching chess engine  competitions.   He enjoys Japanese enka songs, traditional Korean music, opera, and a variety of other music.

Fassil Bekele, M.S.

Reed holds degrees in Mathematics, Computers and Electrical Engineering from the California Institute of Technology and UC Santa Barbara. He has used his science skills as a space engineer, designing satellites, as well as balancing these left brain activities with surfing, music, dance and other more right-brained, artistic and athletic explorations. At Tilden, Reed helps students to break down abstract math or science concepts into their simplest essence, so helping students to achieve mastery whether math and science come easy to the student or not. Reed believes that there are as many different ways to learn as there are people, and that the key to learning is really as simple as a motivated student and an inspiring, caring teacher.

Reed Burkhart, M.S.

Tim obtained a Bachelor of Science degree in Physics and a Bachelor of Arts in Computer Science at UC Santa Cruz. He joined Tilden teaching math and science in 2022 after previous experience as a substitute teacher and a tutor. Tim likes teaching one on one to greatly assist students in how to think, learn and program. 

Tim Burkhart, B.S., B.A.

Will has loved mathematics as far back as he can remember. When he discovered some of the connections between mathematics and music, Will began to dedicate his own time into investigating these interrelationships further. Eventually, he earned his BA in The Mathematics of Music from George Mason University. While tutoring there, he learned that, not only was he good at understanding mathematics, but also able to help others do the same. Soon thereafter, Will earned his Master’s in Education from the University of Phoenix in San Jose. Since then, Will has been teaching, tutoring, and creating curricula for mathematics and electronic music courses for approximately twenty years. When Will is not teaching mathematics or music, he is often exploring them himself. One of Will’s favorite hobbies is cooking vegan food.

Will Beazley, B.A.

Cliff was born and raised in Mexico City until the age of 11. His family decided to move to the United States to seek better education opportunities for his brother and him. While attending College Park High School in Pleasant Hill; Cliff discovered that he had a passion for teaching and helping others with class work. Throughout his high school years, Cliff, his best friend Matt, and his brother held tutoring sessions during lunch in math, French and Spanish. During High School is when he knew he wanted to be a professor/teacher. After high school, Cliff went off to college and received a degree from U.C. Berkeley in Spanish Literature and Language. A couple of years later, he completed a Master's program at San Francisco State. Cliff has tutored middle school and high school students for over 15 years and has taught college level courses for 5 years at D.V.C, St. Mary’s College, and Holy Names in Oakland. When Cliff is not working at Tilden or at one of the colleges, he loves going to the movies and traveling. He spends too much time at the movies!  Another fun fact: he and his brother are twins.

Cliff Escobedo M.A., Foreign Language Department Head

Sam Froehlich has a Bachelor's degree in English from CSU East Bay.  She has always had a passion for literature and English, and loves to help others learn to love reading as much as she does. To learn to read and continue learning in your life beyond school is one of the most important takeaways that makes life more enriching and successful. In her free time, Sam enjoys reading, sewing, painting, baking, gardening, and walking her dog. She also loves comic books, science fiction, and superhero movies! 

Sam Froehlich, B.A.

Claire is a French native who studied business, followed by math and physics, in France. She holds a M.F.A. in Studio Arts from Towson University, MD, and her work has been extensively exhibited on the East Coast, in Illinois, Texas, New Mexico, and Scotland.

From figurative paintings to abstract drawings or installations, her work explores the unspoken, the ignored, and the power of silence. Claire carefully chooses her mediums for their emotional, historical and cultural values, or the implied meanings of their physical properties.  Prior to moving to California, Claire was a lecturer in French and an Adjunct Professor in Visual Arts at Towson University in Maryland and the University of Baltimore. She teaches French at Tilden Prep, and loves sharing anecdotes about the French language with her students. Claire enjoys learning about anything and everything, and in her free time, you will find her outside reading, gardening, hiking, or working on some project.

Claire Girodie, M.F.A.

Lauren is a Bay Area native and has been teaching English for over ten years. She graduated cum laude from Southern New Hampshire University with a Bachelor of Arts degree in English Literature. Before coming to Tilden, she began working toward her Master's in English Literature which she will be completing in the Spring of 2025. On Lauren's journey toward earning her degree, she trained to be an opera singer and subsequently built a business teaching private voice and piano lessons. Though music is a passion of Lauren’s, reading was her first love. To this day, Lauren is just as passionate about reading as she was in first grade and is excited to help her students realize their passion and talent for reading and writing at Tilden. When Lauren is not teaching, she loves to spend time with her family and her dog, garden, and attend live performances

Lauren Gatzka, B.A.

Susana earned her degree in Earth Science from UC Santa Cruz. She previously worked as a former physics and math tutor at Los Medanos College for STEM majors. She also has previous experience working with middle and high school students as a private tutor. Susana formulates her lessons to best suit the student's individual needs. Susana believes students need repetition, encouragement, and constant participation in order to feel the desire to learn. She also believes that learning is a physiological activity which involves the body as a whole. Susana loves drawing and hiking as she enjoys being outdoors in nature. She has run the Mt. Diablo Summit twice. Susana teaches math, science, and foreign language.

Susana Maltez, B.S., Science Department Head

Paris is a passionate educator with two years of teaching experience. Born and raised on the beautiful island of Guam, Paris developed a deep appreciation for nature and the environment from an early age. Before transitioning to teaching, Paris dedicated time to animal rehabilitation, wildlife conservation, and environmental research, working across the Pacific. This hands-on experience with diverse ecosystems and species shaped Paris’s commitment to sustainability and education. Paris now brings that same passion and knowledge into the classroom, inspiring students to care for the world around them while fostering a love for learning.

Paris Marler, B.S.

Ilana McDonald is a Bay Area native who has grown up in advocacy spaces supporting school aged children with educational, social and emotional needs. Ilana is an educator who infuses creativity, self-love, and personal growth into every lesson. She believes in empowering students to explore their potential and express themselves authentically. With experience teaching environmental science in the Monterey Bay Area, she has cultivated a love for sharing knowledge on environmental matters. Passionate about integrating education, healing, and the environment, Ilana nurtures curiosity and resilience in her students. She holds a Bachelor of Arts in Social and Behavioral Sciences with a concentration in Sociology from CSU Monterey Bay and is always on the lookout for personal development in and outside of the classroom.

Ilana McDonald , B.A.

Will joined Tilden’s faculty as a math, science, and humanities teacher in 2022. Will majored in Philosophy at UC Berkeley after having achieved his Associates degree in Chemistry. Will had previous experience as a tutor. 

Will Ranney, B.A.

Prior to becoming Assistant Head of School at Tilden Prep, Alistair taught English and History at Tilden’s Sausalito Campus (now Headlands Prep) for four years.  He loves teaching and is constantly inspired by student successes and breakthroughs. He is excited to bring his knowledge and skill set to our Walnut Creek Campus and be of service to our school community in his new administrative role.  Alistair was born and raised in San Francisco, and he and his family now make their home in Martinez.

Alistair Rogers, M.A., History and Social Science Department Head

Geoff is an East coast transplant who dreams of never leaving the West coast. He has an M.A. in Anthropology from U.C. Berkeley and worked as an archaeologist in California and Peru. Prior to joining Tilden in 2023, he was teaching Social Science sections and writing courses at UC Berkeley. He has a great love of History, Sociology, as well as Earth and Biological Sciences. Geoff can be found in his off-time hiking, trying new recipes, petting cats, and searching bins at his local comic shop.

Geoff Taylor, M.A.

Cristian was born and raised in Viña del Mar, Chile, a city by the beach. There he obtained his degree in Education and a major in English Pedagogy at Saint Thomas University. Cristian has always been a very passionate person, especially in sports and music. During his childhood, he was part of his high school’s soccer team and was awarded as top scorer of the tournaments multiple times. Cristian also taught himself to play guitar and performed in a band. At the age of 22, he became an English Teacher. One week after his graduation, he started working as a head teacher of a 6th grade class at a very prestigious school from his hometown. After three years of teaching English as a foreign language, Cristian moved to the United States where he has been working as a Spanish teacher and tutor.  He joined the Tilden faculty in 2015. Cristian is a very dedicated teacher who focuses his teaching style on helping students believe in themselves by using their strengths and working hard to improve their areas of need. As a Tilden Prep Spanish teacher, he is willing to give a 100% in order to assist students in achieving their individual goals and objectives. When Cristian is not working, he loves spending time playing music, singing, playing tennis and soccer, and spending time with family.

Cristian Vera B., B.A.

Joseph graduated from UCSC in 2016 with a BA in English Literature. He really enjoys teaching and that is mainly what he has been doing since graduation. Joseph’s hobbies include: hiking, playing guitar, reading novels, and learning foreign languages. Joseph became part of the Tilden faculty in 2018 where he teaches humanities.

Joseph Vincent, B.A., English Department Head

Lucas Velasquez brings a passion for science and a wealth of industry experience to the classroom. With a Bachelor’s of Science in Physics from California State University Los Angeles, Lucas combines a deep understanding of scientific principles with real-world applications.  Before transitioning to education, Lucas spent six years in the biotechnology industry, where he held various roles in Quality Control, Formulation, and Quality Assurance. His expertise in engineering troubleshooting practices, developing cost-efficient systems, and ensuring product safety has equipped him with valuable problem-solving skills and a keen attention to detail. Lucas is dedicated to inspiring students through dynamic lessons that bridge complex scientific concepts with practical experiences. He believes in cultivating curiosity and encouraging analytical thinking to prepare the next generation of innovators. Outside of teaching, Lucas enjoys staying active through running and continuously expanding his knowledge of emerging technologies.

Lucas J. Velasquez , B.S.