Chalk produce, and thus widely used in the developing world, calcium-based chalk can be made where the crumbling particles are larger and thus produce less dust, and is marketed as "dustless chalk". Colored chalks, pastel chalks, and sidewalk chalk (shaped into larger sticks and often colored), used to draw on sidewalks, streets, and driveways, are primarily made of gypsum. Chalk is a source of quicklime by thermal decomposition, or slaked lime following quenching of quicklime with water. In southeast England, deneholes are a notable example of ancient chalk pits. Such bell pits may also mark the sites of ancient flint mines,
Blackboard Inc. On July 1, 2011, Blackboard agreed to a $1.64 billion buyout by an investor group led by Providence Equity Partners, completed on October 4, 2011. Following the sale, Providence Equity Partners merged Edline, its K-12 learning system, with Blackboard. Edline was later renamed Blackboard Engage. According to a TechCrunch article from 2012, despite its success, Blackboard had become "one of the most disliked — even detested — companies in education." In December 2011, "Fast Company" reported that 93% of respondents to the Amplicate customer opinion survey "hate" the company. In September 2017, Blackboard announced its expansion to the Indian Educational