Chalk It is formed in the sea by sub-microscopic plankton, which fall to the sea floor and are then consolidated and compressed during diagenesis into chalk rock. Most people first encounter the word "chalk" in school where it refers to blackboard chalk, which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased. Blackboard chalk manufacture now may utilize mineral chalk, other mineral sources of calcium carbonate, or the mineral gypsum (calcium sulfate). While gypsum-based blackboard chalk is the lowest cost to
Devil sticks Devil sticks The manipulation of the devil stick (also devil-sticks, devilsticks, flower sticks, gravity sticks, or juggling sticks) is a form of gyroscopic juggling or equilibristics, consisting of manipulating one stick ("baton", 'center stick') between one or two other sticks held one in each hand. The baton is lifted, struck, or stroked by the two control sticks ('handsticks', 'sidesticks', or 'handles'), stabilizing the baton through gyroscopic motion. Devil sticks are believed to have originated in China in the distant past, in the form of simple wooden juggling sticks. Manipulating devil sticks is one of the circus arts and is sometimes