The textured covers of these notebooks have the feel of old textbooks, and with advanced lay-flat pages, they want to fall open, like a well-loved library book. Go ahead and see for yourself – these are the notebooks your most brilliant ideas have been waiting for. Each Series has a different style of pages. Dark Matters: Includes: Skeleton, Spiders and Webs, Into the Earth Caves, The Edge of the Atmosphere Each cover in the Dark Matter series celebrates the beauty found in darkness and the scenes made by the faintest light. Let your creativity run wild in the black pages of this Bioluminescent Mushrooms Notebook. This extra-thick 120 gsm black paper works great with gel pens (for the brightest colors, look for ones that are formulated to work on dark media, like our Supernova Pens), metallic pens, pastels and even some paints! Sketch/Theory: Includes: Gems & Minerals, Honey Bee, Star Map, Woodland The Theory series is built with extra-thick, high-quality 100% recycled paper and printed with soy inks, leaving a light footprint. Be inspired to ask the right questions, find creative solutions to complex problems, and beauty in the little things. Hypothesis: Includes: Brain, Cardiology, Anatomical Heart, Mushrooms The Hypothesis series is built with high-quality 100% recycled paper and printed with soy inks, leaving a light footprint. Be inspired to ask the right questions, connect the dots (even when they’re really far apart), and keep pushing humanity forward, so that tomorrow is always brighter than today.