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 Most people first encounter the word "chalk" in school where it refers to blackboard chalk, which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased.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
Blackboard Inc. Blackboard Inc. Blackboard Inc. is an educational technology company with corporate headquarters in Washington, D.C.. It is known for Blackboard Learn, a learning management system. The company's CEO is William L. Ballhaus, formerly president and CEO of SRA International, who was also named chairman and president on January 4, 2016, following the resignation of Jay Bhatt, who had led Blackboard since October 2012. The firm provides education, mobile, communication, and commerce software and related services to clients including education providers, corporations and government organizations. The software consists of seven platforms called Learn, Transact, Engage, Connect, Mobile, Collaborate and Analytics that