Two asides about the map. First, the Lewis and Clark map was made with StoryMapJS, a product of the Northwestern University Knight Lab. I love StoryMapJSt! I've already assigned my students two projects this year where they would make maps with this interactive tool. Here's my favorite tutorial (8:46) on how to use it:
Second, the Institute generously supports a wide array of programs and resources for school teachers. (Full disclosure: I was accepted to attend a Gilder Lehrman summer teacher seminar several years ago, at Oxford (!) (yeah, that one), on the age of Lincoln). Information is available by clicking here.