PORTLAND — The third annual Portland Public Schools STEM Exposition will be Friday, Nov. 4, at at the University of Southern Maine’s Sullivan Gymnasium.

The event is a partnership with EnviroLogix, a Portland-based company that creates testing solutions for detecting GMOs, mycotoxins, molds, pathogens, algal toxins and pesticides.

More than 1,800 visitors and presenters are expected at the event, running from 9 a.m. to 2 p.m., when PPS students, post-secondary students, local businesses and others will present their projects in science, technology, engineering and math.

There will be about 50 different presenters at the event; roughly half will be PPS students.

The expo will be open to the public from 9:30 a.m.-1 p.m.