Small coincidences. They happen all the time and yet, they pass us by because we are not looking for them. In a delightfully subtle trick, magician Helder Guimarães demonstrates with a deck of cards, a dollar bill and a stuffed giraffe.

City agencies have access to a wealth of data and statistics reflecting every part of urban life. But as data analyst Ben Wellington suggests in this entertaining talk, sometimes they just don't know what to do with it. He shows how a combination of unexpected questions and smart data crunching can produce strangely useful insights, and shares tips on how to release large sets of data so that anyone can use them.

How do vaccines prevent disease -- even among people too young to get vaccinated? It's a concept called "herd immunity," and it relies on a critical mass of people getting their shots to break the chain of infection. Health researcher Romina Libster shows how herd immunity contained a deadly outbreak of H1N1 in her hometown. (In Spanish with subtitles.)

Rob Knight is a pioneer in studying human microbes, the community of tiny single-cell organisms living inside our bodies that have a huge — and largely unexplored — role in our health. “The three pounds of microbes that you carry around with you might be more important than every single gene you carry around in your genome,” he says. Find out why.