blackboards

A blackboard, also known as a chalkboard, is a smooth, dark surface used for writing with chalk. It is commonly installed in classrooms and lecture halls, enabling instructors to present information to a room.

Historically, blackboards were made from natural slate. Modern boards often consist of porcelain-enamel coatings on steel, or composite boards with a baked-on enamel surface. The color can be black, green, or dark gray depending on the finish; "green boards" are common in some regions.

Chalk—a soft, limestone-based mineral powder—is used to write on these surfaces. Chalk can produce a dusty residue, though dustless chalk and liquid chalk alternatives reduce airborne particulates. Erasers or damp cloths remove chalk writes; over time the surface may ghost or retain marks, requiring resurfacing or replacement.

The blackboard gained widespread use in the 19th and early 20th centuries as literacy and schooling expanded. With the rise of whiteboards in the late 20th century and digital projectors, the role of traditional blackboards has diminished in many settings, though they remain in use in many schools and institutions for certain tasks.

Care and maintenance include regular cleaning with a damp cloth or eraser, avoiding harsh cleaners on certain surfaces, and periodic resurfacing or replacement to limit ghosting. Some boards are magnetic, allowing attachments like notes or maps.