Let’s Build is a family volunteering initiative bringing engineering into Needham’s elementary schools by training family and community volunteers to support classroom design challenges.  Its major fundraiser, the Let’s Build Engineering Extravaganza, will be held April 28, 10AM-2PM at Broadmeadow Elementary School (120 Broad Meadow Rd, Needham) for Pre-K, elementary, and middle-school children and their families.  Suggested donation is $5 per family.  Scheduled activities include an inflatable planetarium, catapults in “The Real Angry Birds,” visualization of sound, Hot Wheels: Exploring Speed and Distance, the physics of rhythmic gymnastics, Hoppers with Olin College, make a hovercraft and more!