Hundreds of elementary and high school students are putting their brain power to work at the 30th annual Chico Science Fair. The showcase opened today at the Silver Dollar Fairgrounds and features roughly 450 exhibits. Nearly 800 students participated, testing everything from how sound waves work to what materials are best for absorbing oil. The free event runs until 8 p.m. tonight and will open back up at 10 a.m. tomorrow morning. The science fair will wrap up with an awards ceremony starting at 6 p.m. Thursday night.