Today I Found Out

Why You Used to Have to Use Number 2 Pencils on Scantrons (and Why Pencil "Lead" is Called Lead) (2017x77)

Data de estreia: Mar 30, 2017

→Subscribe for new videos every day! 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&section_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 https:/