During the initial portion of a training flight in the tailwheel-equipped amateur-built airplane, the flight instructor demonstrated two takeoffs and landings to the pilot. The pilot then assumed the controls and began the takeoff roll. The flight instructor directed the pilot to rotate the tail of the airplane into the air by increasing nose down pitch. According to the flight instructor, the pilot did not add enough forward pressure and the airplane seemed like it was still in a nose high attitude. The flight instructor then assisted the pilot by pushing forward on the control stick to what looked like a level attitude. The propeller struck the ground and the airplane nosed over, coming to rest inverted. The airplane sustained substantial damage to the tail and right wing. Both pilots noted no preimpact mechanical malfunctions or failures that would have precluded normal operation. Neither pilot had any previous experience performing takeoffs or landings in the accident airplane make and model.