Barbara Morgan, flanked by crewmates Alvin Drew and Dave Williams, talked for 25 minutes to children at the Discovery Center in Boise, Idaho, the north-western state where Morgan taught at a primary school early in her career.
"Astronauts and teachers actually do the same thing. We explore, we discover and we share," she told the class via videolink. "Those are absolutely wonderful jobs."
Mrs Morgan, now 55, trained as understudy to fellow teacher Christa McAuliffe in the 1980s, as NASA hoped that sending a teacher into space would fire the imaginations of millions and keep up support for its shuttle program.
But McAuliffe never made it to space. The Challenger shuttle exploded shortly after take-off in 1986, killing all seven people on board.
Twenty-two years later, Mrs Morgan has fulfilled the aim, riding aboard the shuttle Endeavour on a construction mission to the International Space Station.
In a session broadcast to Earth by the space agency NASA, she fielded questions such as how fast a baseball travels in space, and how to drink in zero-gravity.
She and her fellow astronauts demonstrated, throwing real balls and swallowing floating bubbles of liquid.
Asked how astronauts exercise in space, Mrs Morgan grabbed one of her colleagues and lifted him.
Mrs Morgan returned to teaching after the Challenger disaster, but in the 1990s started six years of training in the astronaut corps.
She is the star of this year's second shuttle mission to the International Space Station.
NASA is seeking to burnish an image tainted by recent scandals including stories that astronauts had shown up for missions drunk, and a bizarre love-triangle vendetta involving a female astronaut and her married colleague.
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