When a team of archeologists recently came across some 15,000-year-old human remains, they made an interesting discovery: the teeth of those ancient humans were riddled with holes. So what causes cavities, and how can we avoid them? Mel Rosenberg takes us inside our teeth to find out. Lesson by Mel Rosenberg, animation by Andrew Foerster.
Click on the link to access the full lesson:
https://ed.ted.com/lessons/what-causes-cavities-mel-rosenberg#watch
It may seem like the semicolon is struggling with an identity crisis. It looks like a comma crossed with a period. Maybe that’s why we toss these punctuation marks around like grammatical confetti; we’re confused about how to use them properly. Emma Bryce clarifies best practices for the semi-confusing semicolon. Lesson by Emma Bryce, animation by Karrot Entertainment.
Outside of China, Mandarin and Cantonese are often referred to as Chinese dialects, despite being even more dissimilar than Spanish and Italian. On the other hand, speakers of Danish, Norwegian, and Swedish, which are three distinct languages, can usually communicate with each other in their native tongues. So, when is speech considered a dialect versus a language?
Katherine Reilly 