More than 600 kids participated in hands-on scientific demonstrations from local companies and colleges at Bangor's Cross Insurance Center.
The festival opened Thursday and runs through Sunday. This is the fourth year of the annual event.
Event organizers say the festival is a chance for people to see what Maine has to offer, in numerous scientific fields.
"If you are interested in technology, you need to know science. If you want to program an app, you need to know science and engineering," said the Maine Science Festival Director Kate Dickerson. "So anything we do from this point on in society, you need to understand how science works. And you can do it all here in Maine, which is kind of the whole point of this festival, showing who in Maine is doing this work."
Organizers said while Friday's event was for school field trips, the rest of the weekend will have events for all ages.
The festival will host events Saturday at the Cross Insurance Center, and Sunday in Downtown Bangor.
Almost every event is free. A schedule of events can be found on the festival's website.