Jericho High School teacher Nicole Izzo wasted no time Tuesday before launching into the lesson, asking her business students what Apple, Disney and Google have in common.

They were start-ups, one student observed. More precisely, they began in an inventor’s garage, said another, banging his hand on the table as classmates responded to the query.

“Some of the great ideas can really start small,” Izzo said.

School has begun on Long Island. Jericho was first — the only school system, among 124 in Nassau and Suffolk counties, to launch Tuesday. The rest are staggered over the course of this week and next, with the majority of districts holding the first day of class on Sept. 5 or Sept. 6.

Jericho and five other systems scheduled the first day this week.

“A longer school year is better; a longer school day is better,” Jericho Superintendent Henry Grishman said.

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At 8 a.m., the district’s youngest students walked off school buses at George A. Jackson Elementary School, some crying, others with their sibling’s arm around their shoulders, and lined up in the back of the building on the blacktop with their teachers — a longtime school tradition.

Elsewhere on the Island, preparations were underway with staff development training.

In Herricks, where classes start Wednesday, “staff is prepared and ready to go,” Superintendent Fino Celano said. The district is launching new STEM initiatives and the 2017-18 curriculum will emphasize social and emotional learning as well as mindfulness and expanded yoga offerings for all students.

Deirdre Bambrick, a second-grade teacher at Searingtown Elementary School, has written a song for her class and is planning an exercise that emphasizes mindfulness.

“Sometimes kids are so overwhelmed . . . just taking that moment or two to have mindful moment will set the course for the day or the class you’re teaching,” Bambrick said.

The William Floyd school district begins classes Friday for students in kindergarten through ninth grade, and other high school students start next Tuesday.

New this year is a “Freshman Academy,” consisting of reconfigured space in the high school for the ninth-graders, as well as an alternative elementary program. On Thursday, the district will welcome 40 new teachers.

“We’re continuing to try to drive that graduation rate up,” Superintendent Kevin Coster said.