Today I Found Out
Why You Used to Have to Use Number 2 Pencils on Scantrons (and Why Pencil "Lead" is Called Lead) (2017x77)
Air date: Mar 30, 2017
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https://www.youtube.com/→“plumbago”, which is derived from “plumbum”, which is Latin for “lead”.
Want the text version?: http://www.todayifoundout.com/index.php/2010/11/why-pencil-lead-is-called-lead/
Sources:
http://www.pencils.com/unleaded-pencil
http://www.pencils.com/pencil-history
http://www.abc.net.au/science/articles/2004/09/09/1195234.htm
http://www.etymonline.com/index.php?term=lead
http://www.todayifoundout.com/index.php/2010/10/why-you-used-to-have-to-use-2-pencils-with-scantron-forms/
http://en.wikipedia.org/wiki/Pencil
http://en.wikipedia.org/wiki/Lead
http://www.mentalfloss.com/blogs/archives/57276
http://www.objectlessons.org/index.php?mod=PageMod.showComponent§ion_id=5&category_id=19&component_id=146&component_type=feature
http://www.penciltalk.org/images/penciltalk.org.leads.4.jpg
Image Credit:
https://www.bigstockphoto.com/ru/image-84807116/stock-photo-female-hand-filling-test-score-sheet-with-pen
https://www.bigstockphoto.com/ru/image-22117256/stock-photo-%D0%9F%D1%80%D0%BE%D1%85%D0%BE%D0%B6%D0%B4%D0%B5%D0%BD%D0%B8%D0%B5-%D1%82%D0%B5%D1%81%D1%82%D0%B0
https://www.bigstockphoto.com/ru/image-6233725/stock-photo-%D0%A2%D0%B5%D1%81%D1%82-%D0%B2%D0%B8%D0%BA%D1%82%D0%BE%D1%80%D0%B8%D0%BD%D1%8B
https://www.bigstockphoto.com/ru/image-20684300/stock-photo-%D0%9F%D1%80%D0%BE%D1%85%D0%BE%D0%B6%D0%B4%D0%B5%D0%BD%D0%B8%D0%B5-%D1%82%D0%B5%D1%81%D1%82%D0%B0
https://www.bigstockphoto.com/ru/image-2898911/stock-photo-scantron-%D0%B8-%D0%BA%D0%B0%D1%80%D0%B0%D0%BD%D0%B4%D0%B0%D1%88
https://www.bigstockphoto.com/ru/image-6233691/stock-photo-%D0%A2%D0%B5%D1%81%D1%82-%D0%B2%D0%B8%D0%BA%D1%82%D0%BE%D1%80%D0%B8%D0%BD%D1%8B
https://www.bigstockphoto.com/ru/image-374326/stock-photo-%D0%96%D0%B5%D0%BB%D1%82%D1%8B%D0%B9-%D0%BA%D0%B0%D1%80%D0%B0%D0%BD%D0%B4%D0%B0%D1%88
https://www.bigstockphoto.com/ru/image-3167040/stock-photo-%D0%9B%D0%B8%D1%81%D1%82-%D0%BE%D1%82%D0%B2%D0%B5%D1%82%D0%BE%D0%B2
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