We have changed how we collect and accept calendar information. Readers must now submit all items through our website. Go to events.contracostatimes.com, click on "submit your event," register and then enter your event. You do not have to pay. Submitting your event in this way will ensure it is part of our easily searchable online database, as well as a candidate for space in our publications.
Oakland Public Library Book Sale. The Bookmark Bookstore's semiannual book sale features scores of books at reduced prices. Prices get slashed as the sale goes on. Members get special rates. 10:30 a.m. to 5:30 p.m. through April 13. The Bookmark Bookstore Friends of the Library, 721 Washington St., Oakland. Free. 510-444-0473, fopl.org/bookmarkbookstore.
HNU Spring Orchestra Concert. The Holy Names University Orchestra presents their spring concert led by music director Steven F. Hofer. 3 p.m. April 13. $10 general. $5 seniors/students. Holy Names University, Regents Theatre, 3500 Mountain Blvd., Oakland. 510-436-1404, www.hnu.edu.
Oakland Symphony Chorus. Music Director Lynne Morrow is at the helm and Rudy deVos, Shawnette Sulker, Amy Bouchard, Darron Flagg and Zachary Gordin perform when the Oakland Symphony Chorus present Handel's "Messiah." Audience singalong encouraged. 5:30 p.m. April 13. Cathedral of Christ the Light, 2121 Harrison St., Oakland. $20. www.oaklandsymphonychorus.org.
Red Cross Orientation Meeting. American Red Cross Northern California Region holds a volunteer orientation for people interested in working with blood donors, delivering blood, and helping with special projects. Registration required. 3:30 p.m. April 17. Oakland Blood Donation Center, 6230 Claremont Ave., Oakland. 510-594-5165, email@example.com.
Crew Creek Work Day. Volunteers needed to clean up Arroyo Viejo Creek. Don gardening gloves, wear closed-toe shoes and work clothes, bring water and snacks. Chaperones needed for youth volunteers. At noon, folks get a free pass to the Oakland Zoo. RSVP appreciated. 9 a.m. to noon. April 19. Oakland Zoo, 9777 Golf Links Road, Oakland. 510-632-9525, firstname.lastname@example.org.
Free Computer Tutoring. Brush up on your computer basics at free computer tutoring. 1 to 3 p.m. Saturdays. 4 to 6 p.m. Tuesdays. Rockridge Branch Library. 5366 College Ave., Oakland. 510-597-5017, www.oaklandlibrary.org.
Peralta Hacienda Kids Club. Kids from 5 to 15 can play and experience Oakland's original rancho through traditional arts and hands-on activities: Make adobe bricks and corn husk dolls, learn about native plants and make seed balls, traipse through the creek area and participate in other nature-based tours. 2:30 to 5 p.m. Saturdays. Peralta Hacienda Historical Park, 2465 34th Ave., Oakland. Free. 510-532-9142, www.peraltahacienda.org.