The Samuel J. Tilden High School in East Flatbush was built in 1927 and retains the gray fortress-like look of a public institution where children are held captive to learn — or else. Today almost a century later the austere ambience is amplified by 21st-century technology: All who enter here must pass through metal detectors and surrender their bags for scanning. Once inside however the atmosphere lightens: Now we are in the hallways of a regular public school with colorful bulletin boards and displays of students’ artwork. The mostly minority students look cheerful enough as a culturally diverse group of teachers shepherds them from classroom to classroom. The far left wing ofTilden however houses a different educational creature: a charter school entitled The New American Academy. The Academy’s lottery-selected students range from kindergarten through third grade with a higher grade added each year as the students move up. The brainchild of six principals enrolled in the Harvard Urban Superintendent doctoral program it offers integrated instruction taught by teams of teachers who stay with the same students year by year and has been hailed as a model for helping disadvantaged students succeed. The academy’s founder Mr.ShimonWaronker was one of the six original visionaries and the only one to actually implement the group’s ideas (the others took positions as superintendents). Now in his early 40s Waronker adds his own note of diversity toTilden: In addition to his tweed jacket and tie he wears a yarmulke and a dark beard only beginning to show threads of gray. Raised in South America to Jewish-identified but largely nonpracticing parents he spent time in the US Army before becoming a Lubavitcher chassid and teacher.