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 Inc. the deployment options of Blackboard Learn to include public cloud, and improvements to Blackboard's mobile app. , Blackboard serves approximately 17,000 schools and organizations. It holds the highest share of the education market with 75 percent of colleges and universities and more than half of K-12 districts in the US using its products and services. , Blackboard had acquired MyEdu, Perceptis, and CardSmith, and Requestec under Bhatt's leadership. The acquisitions reflected Bhatt's new acquisition strategy of making investments that serve students and will lead to innovations in Blackboard's core teaching and learning products. Blackboard has used the acquisition of other