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 Most people first encounter the word "chalk" in school where it refers to blackboard chalk, which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased.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
Chalk talk (1842-1905). Today chalk talks are still regularly used as a method of preaching scripture visually, by evangelists that have artistic ability. A book by Jeanne Bridge, "Chalk Talk for Catechists," gives us a useful introduction to a catechetical method, where we see (what?) is an increasing interest among all sectors of people. Basically, it talks about "speaking the message" by illustrating with simple chalk drawings, along with the talk, that highlight the main points of the lesson. The word which is predominant is at a lead together with the word [this phrase says nothing], so that the word and the