Thordis W. Burkhardt, 85, a studio teacher whose pupils included "Lassie's" Jon Provost. Married to artist Hans Burkhardt, she began teaching child actors in studio sets and dressing rooms after hearing at a 1955 dinner party that such a career was available. She continued the work under the auspices of the Los Angeles Unified School District for 20 years, teaching Provost for four years. Her other pupils included Anissa Jones, who portrayed Buffy on the television show "Family Affair;" Jerry Mathers and Tony Dow, the Beaver and Wally of "Leave It to Beaver," and the children in the film "The King and I." On Nov. 5 in Los Angeles.