Biology, engineering, computer science. These are just a few of the subjects kids will encounter at the annual free North Bay Science Discovery Day. With more than 100 hands-on activities, the annual fair aims to encourage kids to explore the many dimensions of science, including chemistry, technology, and math. It will be held on May 15, 10 a.m.–4 p.m., at the Sonoma County Fairgrounds in Santa Rosa. Admission and parking are free. Masks and proof of COVID-19 vaccination or a negative COVID-19 test are required for entry. See northbayscience.org for details.