thanks to our guest, francois vannel, deborah snyder and jen lopes. the harlem hell fires, the under dogs that shocked the world. >> 360 night, never lost a battle. while they lost many men, they never lost an inch of ground for 191 days, they stood on that battlefield supported not by americans but by the french. >> so why haven't we heard more about these world war i heroes? their story in two minutes. you don't want to miss it. >> i'm at the national wind institute, where they can create tornados... >> a greater understanding... >> we know how to design for the wind speeds, now we design for... >> avoiding future tragedies >> i want a shelter in every school. >> techknow every saturday, go where science, meets humanity. >> this is some of the best driving i've ever done, even though i can't see. >>techknow >> is there an enviromental urgency? only on al jazeera america chasing bail only on al jazeera america >>> this memorial is the best way. the stars and wreaths and each state is showing our nation worked together to do this. >> we are discussing