"Hello, I would like some slate please, and make it extralarge this time!"
Long ago we used to write on slates with a little stick!
She wrote her daily schedule on a slate hung by the door.
At school it was normal to write with a slate penicil on a piece of slate (the slate pencil could be make of clay, soft slate, soapstone or chalk). The main advantage of slate was that it the marks could be erased and the slate could be reused.
slate boards
slate
You write on a blackboard.
Victorian slate boards were mostly used by children in schools. Children used slate boards to learn how to write and spell.
After the mistake, she decided to start fresh with a clean slate.
Chalk is softer than the slate (real or artificial) used on blackboards, so it will flake off as you write. Granite is harder than slate and will not flake, but rather cut into or mark the slate permanently.
a slate
Rough when it is fresh but when shaped it is smooth and cold. Slate is used as chalkboards. It is smooth, cool or cold to the touch, and chalk can leave 'marks' so humans can write or draw on its surface. Slate has been used for centuries in school (students used a single small "slate" to do their "figuring" -math- and to write words or sentences.
Actually, the word "slate" does not rhyme with "kneel," as they have different vowel sounds. "Slate" rhymes with words like "great" and "late."