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. and notifications, academic or instructor notifications, or by school districts and communities to share time-sensitive information, such as in the case of natural disasters and campus emergencies. Blackboard Transact, formerly Blackboard Commerce Suite, is transaction processing system tied to university ID cards, which can be used for meal plans, vending machines and laundry services, and an e-commerce front end for the transaction system. The Transact system is NFC-compatible and its ID cards use contactless technology. Blackboard Transact also includes a program for off-campus vendors that allow students to pay for goods using their college's campus card. Blackboard Analytics was developed