Author name: Threeyzmonkeys

#140 How does an eraser work?

I learned this today. Erasers work because of friction. They become sticky when they are hot and hold onto the graphite particles. Before we look at how erasers work, I think we need to look at how pencils are able to write on paper. Pencils are made with graphite. These days the graphite is mixed

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#139 What are the six great mass extinction events?

I learned this today. There have been six mass extinctions on Earth that experts know about. The Great Oxidation Event about 2.4 billion years ago. The Ordovician-Silurian Extinction 440 million years ago. The Devonian Extinction 365 million years ago. The Permian-Triassic Extinction 250 million years ago. The Triassic-Jurassic Extinction 210 million years ago. The Cretaceous-Tertiary

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