A popular Los Angeles high school science teacher has been suspended after students turned in projects that appeared dangerous to administrators, spurring a campaign calling for his return to the classroom.

Students and parents have rallied around Greg Schiller after his suspension in February from the downtown Cortines School of Visual & Performing Arts. Supporters have organized a rally on his behalf at the campus scheduled for Thursday, gathered hundreds of signatures on a petition calling for his reinstatement and set up a social media page.

Schiller was ordered to report daily to a district administrative office pending an investigation after two students turned in science projects that were designed to shoot small projectiles.

One project used compressed air to propel a small object, but it was not connected to a source of air pressure, so it could not have been fired. (In 2012, President Obama tried out a more powerful air-pressure device at a White House Science Fair that could launch a marshmallow 175 feet.)

Another project used the power from an AA battery to charge a tube surrounded by a coil. When the ninth-grader proposed it, Schiller told him to be more scientific, to construct and test different coils and to draw graphs and conduct additional analysis, said the student's parents, who also are Los Angeles teachers.

A school employee saw the air-pressure project and raised concerns about what looked to her like a weapon, according to the teachers union and supporters. Schiller, who said he never saw either completed project except in photos, was summoned and sent home.

Both projects were confiscated as “evidence,” said Susan Ferguson, whose son did the coil-gun project.

L.A. Unified School District administrators have told Schiller that he was removed from his classroom six weeks ago for “supervising the building, research and development of imitation weapons,” said union representative Roger Scott.