the chalk used to write on the blackboard makes a squeaky sound

The full stop or, instead, a virgula, i.e. a short slanting strike (/) is used... to mark the end of a sentence or of a portion of a sentence followed by a pause.

MARIE KONDO'ING MY KITCHEN: What a food writer learned from a total pantry re-org with a food-waste expert

One looked like a taco-bender: olive skin and long dark hair tied back in a ponytail. Dynamite body, looked about twenty-five.