VIRTUAL Air & Space at Your Place: Time Machines. Travel back in time to journey through the beginnings of aviation! Explore the four forces of flight and experiment with what it takes to get your inventions off the ground. Build a kite, a bird or butterfly glider, an early flying machine, and wind-up helicopter toy like the one that fascinated the young Wright brothers. Four-week sessions, Apr. 7, 14, 21 & 28. Wednesday, 3-4 pm. For grades 2-5. $75 includes materials. Register at www.sandiegoairandspace.org.