up next, author karla killough mcclaferty recalls a project where historians and scientists set off to understand what the first u.s. president looked like in different moments of his life. this event was filmed in 2012 in little rock, arkansas. >> i have written nonfiction books on a wide variety of topics from george washington to x-rays to marie currie to an american holocaust rescuer, to tech titans like bill gates and steve jobs and others. when i begin a project, i know little about my topics. i begin to do the research, i go on a treasure hunt that's the way i like to look at it. i use primary sources in order to gather the material that i need to write nonfiction books that are accurate and interesting as well. so when i began to look into this book about george washington and decided to write this book, i began to write about george washington in the same way. i knew little about washington. i heard, of course, he chopped down the cherry tree, which he didn't. i heard he wore a wig, which he didn't. and i'd heard that he wore wooden teeth, which he didn't. so i found out every