By James N. McKean The worst piece of playground equipment in days of old was the see-saw. They’re mainly extinct now, and had a predatory look to them: a long pole, balanced in the center, with a seat at each end. You’d see tiny children rising high into the sky—soaring, un-helmeted, ten feet above the … Continue reading The Key to Neck Stability—and String Height—Appeared in the Playgrounds of Old