I love the way this article gave a hands-on activity that makes the science real for students! Presenting the idea of gravity alongside the smallest-possible surface area is a great explanation for why the earth "MUST be round." Furthering the discussion by having students compress playdough as tightly together as possible puts the results into their hands. Squeezing together playdough from all sides will make a ball (sphere). The children compressing represents gravity and the playdough represents Earth. This is a memorable activity that will make students excited to learn and myself excited to teach it!