Diana Laufenberg shares three surprising things she has learned about teaching -- including a key insight about learning from mistakes.

In the century-old statues that occupy Cape Town, Sethembile Mzesane didn't see anything that looked like her own reality. So she became a living sculpture herself, standing for hours on end in public spaces dressed in symbolic costumes, to reclaim the city and its public spaces for her community. In this powerful, tour-de-force talk, she shares the stories and motivation behind her mesmerizing performance art.

Sculptor and engineer Arthur Ganson talks about his work -- kinetic art that explores deep philosophical ideas and is gee-whiz fun to look at.

Robb Willer studies the forces that unite and divide us. As a social psychologist, he researches how moral values -- typically a source of division -- can also be used to bring people together. Willer shares compelling insights on how we might bridge the ideological divide and offers some intuitive advice on ways to be more persuasive when talking politics.

Myriam Sidibe is a warrior in the fight against childhood disease. Her weapon of choice? A bar of soap. For cost-effective prevention against sickness, it’s hard to beat soapy hand-washing, which cuts down risk of pneumonia, diarrhea, cholera and worse. Sidibe, a public-health expert, makes a smart case for public-private partnerships to promote clean hands — and local, sustainable entrepreneurship.

We're not going to end violence by telling people that it's morally wrong, says Jamila Raqib, executive director of the Albert Einstein Institution. Instead, we must find alternative ways to conduct conflict that are equally powerful and effective. Raqib promotes nonviolent resistance to people living under tyranny -- and there's a lot more to it than street protests. She shares encouraging examples of creative strategies that have led to change around the world and a message of hope for a future without armed conflict. "The greatest hope for humanity lies not in condemning violence but in making violence obsolete," Raqib says.

The human brain is puzzling -- it is curiously large given the size of our bodies, uses a tremendous amount of energy for its weight and has a bizarrely dense cerebral cortex. But: why? Neuroscientist Suzana Herculano-Houzel puts on her detective's cap and leads us through this mystery. By making "brain soup," she arrives at a startling conclusion.

At TED2009, Al Gore presents updated slides from around the globe to make the case that worrying climate trends are even worse than scientists predicted, and to make clear his stance on "clean coal."

After Sarah Gray's unborn son Thomas was diagnosed with anencephaly, a terminal condition, she decided to turn her family's tragedy into an extraordinary gift and donate his organs to scientific research. In this tribute to life and discovery, she shares her journey to find meaning in loss and spreads a message of hope for other grieving families.

When Ebola broke out in March 2014, Pardis Sabeti and her team got to work sequencing the virus's genome, learning how it mutated and spread. Sabeti immediately released her research online, so virus trackers and scientists from around the world could join in the urgent fight. In this talk, she shows how open cooperation was key to halting the virus ... and to attacking the next one to come along. "We had to work openly, we had to share and we had to work together," Sabeti says. "Let us not let the world be defined by the destruction wrought by one virus, but illuminated by billions of hearts and minds working in unity."