Blackboard ‘chalk’ are produced especially for use with blackboards in white and also in various colours. White chalk sticks are made mainly from calcium carbonate derived from mineral chalk rock or limestone, while colored or pastel chalks are made from calcium sulfate in its dihydrate form, CaSO·2HO, derived from gypsum. Chalk sticks containing calcium carbonate typically contain 40–60% of CaCO (calcite). As compared to whiteboards, blackboards still have a variety of advantages: On the other hand, chalk produces dust, the amount depending on the quality of chalk used. Some people find this uncomfortable or may be allergic to it, and according
Blackboard Learn LLC and were developing a software product that would power online education and be scalable for wider institutional application. At the same time, Matthew Pittinsky and Michael Chasen formed Blackboard LLC and were contracted to help lead the formation of the Educause IMS standards group for online education technology. The two groups merged to form Blackboard Inc., which then developed the Blackboard Learning System. In 2015 the company announced a major upgrade to the user experience, called Ultra. According to company statements, Ultra is to be an optional user interface sitting on top of the existing Learn 9.1 architecture. In