Blackboard
A blackboard was a flat vertical surface used for writing on with chalk. 

20th century rocket scientist Robert H. Goddard used a blackboard for his profession. (, opening credits)

A 1960s classroom on  contained a blackboard. ()

Professor 's lair included a blackboard. ()

In 2367, Noonian Soong's laboratory had a green blackboard. ()

Later that year, to Geordi La Forge's amazement, a hologram of  wrote equations on a blackboard as Reginald Barclay looked on and offered suggestions. ()

In 2375, a chalk-drawn plan of Vic's lounge was used to plan the elimination of Frankie Eyes and his henchmen. ()

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Communications technology
Education