Clear the board!

 Clap the erasers.

I wonder if that sentence were posed to children these days, asking for an explanation, would they have any idea?

Blackboards are still sometimes spotted in restaurants or bars featuring the daily special, but it's a rare occurrence.

Schools haven't used blackboards for years.

As for clapping the erasers....

It was one of my favorite chores at school. We would gather up all the erasers, gray-black felt ones covered with white chalk dust, and take them out behind the red brick schoolhouse and, well, clap them! Clouds of dust arose, and we rubbed them up and down against each other to clear them. The urge hit all of us to clap them against the red building, but we only did that once!

The simple economy of it all. The teacher wrote on the board; we copied her words in our notebooks. And don't you think there's a chance we learned more from the effort of seeing and copying - eye/brain/hand - than merely glancing at a handout?

 End of lesson, erase.

 End of week, clap the erasers.

My elementary education in a nutshell!