chalk dust

1. After the horseplay by the wicked students, the classroom floor was strewn with crumbled chalk dust.
   那班顽皮学生闹著玩儿，捏碎不少粉笔，过后，教室地板上撒满了粉笔灰。
2. Yes, the classroom is always a comfortable working condition except some chalk dust still.
   是的，课室虽然还有粉笔尘，但仍然是很舒适的工作环境。
3. The Measurement and Analysis of Chalk-dust Particle Size Distribution
   粉笔尘粒度分布的测定与分析

noun

1. dust resulting from writing with a piece of chalk
   1. chalk dust covered the teacher's hands