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Ordovician Period – limestone and liverwort

By |2018-04-21T11:56:38-07:00June 24th, 2017|Geology|

The Ordovician period saw the evolution of the octopus At the end of the Cambrian period, about 488 million years ago, most of the plants and animals living on Earth died, because of some catastrophe that we don't know much about. This catastrophe marks the beginning of the Ordovician period. Limestone formed Sea [...]

Calcium project – Chalk and lemon juice – Chemistry

By |2019-02-26T05:52:48-07:00June 1st, 2017|Chemistry|

Need chalk? Buy chalk Chalk has calcium in it 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. Some kinds of chalk are made of plaster of paris. You don't want those. What is calcium? More [...]

Calcium – Atoms and Chemistry

By |2019-02-26T05:37:02-07:00June 1st, 2017|Biology, Chemistry|

Chalk cliff (made of calcium atoms) in Cottonwood Canyon, Pueblo, Colorado What is calcium? 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. More about stars And about atoms All our chemistry articles What's [...]

Eggs – Evolution and Biology

By |2019-03-22T08:11:09-07:00May 29th, 2017|Biology|

Fish eggs: Egg evolution starts with soft eggs like these When did the first eggs evolve? The earliest living creatures made babies by dividing themselves in half, so that one cell became two cells. But about 1.4 billion years ago, some creatures with more than one cell began to develop specialized cells that [...]