chalk

Home » chalk

Parchment and the history of books

By |2018-04-21T13:19:57+00:00July 27th, 2017|Literature, West Asia|

Pseudo-Apuleius, Herbarium (about 600 AD, now in Leiden) Scribes carved the first writing on wet clay tablets, but soon after that, about 3000 BC, the Egyptians invented papyrus, and by about 500 BC most people in West Asia and the Mediterranean used papyrus for writing. They couldn't make papyrus, though, because papyrus reeds wouldn't grow in their countries, and they had to buy [...]

Rangoli – Colored patterns – Hinduism project

By |2018-04-16T10:32:23+00:00July 21st, 2017|India, Religion|

A woman creates a pattern with colored sand for Diwali All over India, women use colored rice flour or wheat flour, or colored sand, to make patterns on the ground to celebrate holidays like Diwali. People in India call these patterns rangoli After the celebration, they just sweep up and the floor is clean again. You can make your own rangoli [...]

Calcium project – Chalk and lemon juice – Chemistry

By |2018-04-16T17:38:03+00:00June 1st, 2017|Chemistry|

Need chalk? Buy chalk Take a piece of regular white chalk, like for writing on a blackboard. Make sure the chalk is calcium carbonate like the kind in the picture and not made of plaster of paris. Drop the chalk in a cup of vinegar or lemon juice. Vinegar is made of water [...]

Calcium – Atoms and Chemistry

By |2018-04-16T14:37:53+00:00June 1st, 2017|Biology, Chemistry|

Chalk cliff (made of calcium) in Cottonwood Canyon, Pueblo, Colorado When a star is on the way to converting all of its carbon and oxygen atoms into iron, calcium is one kind of atom it makes along the way. One atom of calcium has 20 protons and 20 electrons (and 20 neutrons). Calcium is a [...]