1. Preheat oven to 400°F.
2. In a large bowl, whisk together flours, wheat germ, salt, sugar, baking soda and cream of tartar in a large bowl. Cut in butter with a pastry blender (or have your kids rub it in with their fingers) until mixture resembles coarse meal. Make a well in center and add buttermilk, stirring until a dough forms.
3. Scrape out dough onto a lightly floured surface and knead just until smooth, about 3 minutes. Form into a free-form round.
4. Transfer to a lightly oiled baking pan. With a sharp knife, cut a ½-inch deep X across top of dough. Bake until loaf is lightly browned and sounds hollow when tapped, around 30 to 40 minutes.
5. Cool on a baking rack for at least 30 minutes. Serve warm with butter and jam.
6.Cool any leftover bread to room temperature and wrap tightly in plastic wrap. Store at room temperature for 1 day; refrigerate for longer storage.