6 incredible musculoskeletal system facts for middle and high school science. Teach bones and muscles with high-engagement hooks: piezoelectric bones, the tiny stapes, femur strength, the “floating” hyoid, bone marrow making 2 million red blood cells per second, and the diaphragm working about 20,000 breaths per day. Includes classroom-ready lesson ideas and a Two Truths & a Lie routine.