A precursor to chalkboards existed during the Roman Empire, where wax tablets were commonly used.

The very first chalkboards were black—hence the name “blackboard.” They were made of slate and pieced together like a puzzle. Chalkboards eventually became green in the 1960s, as the color was found to be easier on the eyes.

One reason chalkboards became popular in classrooms during the 1800s was to reduce the use of paper, which was relatively expensive in the 19th century.

Real chalk is made of limestone, but most modern chalk is actually made of gypsum.

Today, it’s very possible to buy or make a chalkboard using materials that make it magnetic, such as magnetic primer.

The infamous screeching sound of chalk on a chalkboard is caused by high-friction dragging.

There are companies that manufacture dustless chalk for people with allergies or asthma. This is one reason some hospitals ban chalkboards entirely. Chalk dust can also damage electronics.

Japanese schools often prefer chalkboards over whiteboards due to their aesthetically pleasing background.

In some African countries, chalkboards are made from polished concrete painted black.

Traditional chalkboard erasers are made from a combination of felt and wood. While there are many alternatives, one surprisingly effective option for cleaning is Coca-Cola soda.

Wet chalk is actually better than dry chalk for producing cleaner, bolder lines.

Chalkboards often work better than whiteboards for left-handed individuals, as they reduce smudging.

The are chalkboards that have been made to be 100 feet wide.