You can do both with this book—no writin’ required! It’s The Little Book of Mathematical Principles, Theories, & Things, which is a title we love, despite the Oxford comma. By math whiz, author and professor Robert Solomon, the paperback volume has (224) pages. Measures an easily totable 5-1/2" X 7", letting you peruse a lesson on Binary Numbers, The Golden Ratio, Logarithms, Chaos Theory, Russell’s Paradox, Fermat’s Last Theorem, or about 115 others, each (1) to (2) pages long, whenever you have a spare minute to learn.

If you're devoted to explosions, and who isn't, you'll love the new expanded 2nd edition of William Gurstelle's Backyard Ballistics, now 25% longer, with 25% more ka-boomery. Still the go-to reference work for building rockets, cannons (carbide and potato), flingers, fire kites, electromagnetic pipe guns, tennis ball mortars, cleaner-bag balloons, ballistic pendula and petards. You simply can't have more fun with common household materials. The soft-cover, 210pp compendium includes detailed and illustrated instructions, parts lists and sensible ways not to be hoist on your own petard. Be careful out there.

Start them out right with this (profusely) hand-illustrated, 96-page book: The Story of Inventions. Includes toasters, toilets, television, computers, cars, chocolate bars, dishwashers, pianos, flying machines, bicycles and blue jeans among many others. Includes a timeline, glossary and index. No age recommendations, but we like it for pretty much anyone.

Learn atomic weights while winning money from your classmates. Here’s a double deck of (104) cards plus (4) jokers all stored in a stylish box because no one wants to lose their gold, krypton or rubidium. In addition to the standard playing card values, the decks cover the periodic table of elements. Each card includes one element’s atomic number, symbol, series, melting and boiling points, period/group, uses, est. atomic weight, standard state, and the element’s name in English. Includes instructions for (2) educational games if you aren’t in the mood for canasta or two games of hearts. Up to date 6th Edition for all your fraction of a second elements.

50 Science Things to Make and Do is just that, a passel of experiments, all illustratively explained in two facing pages of this big 104-page flip book, and all easily done with common household items. Includes wind and water power, bugs, crystals, paper planes, rubber-band guitars, balances, gloop, optics and a ton of other fun, informative stuff. Officially classified as "cool" by several of our geekiest staffers.

Our grandmother used to tell us that all the time, and we might have learned something while we were out there if she’d given us The Kid’s Guide to Exploring Nature, this 120-page paperback from the Brooklyn Botanic Garden. Chock full of information, photos and illustrations for exploring nature in both the city (includes pigeon info!) and the countryside, and in all four seasons. They might stay out of your hair until supper.

Time was, the Scouts taught tots how to tie a few knots, but that was before John Sherry (knot-instructor par excellence and a member of the International Guild of Knot Tyers) came along with Knot It! a (126)-page hardcover book with illustrated instructions for tying (100) different knots. Our faves are the Schwabisch Hitch and the Slippery Night Loop. Includes a couple of 15” hanks of practice paracord and waterproof cards with (20) knot instructions. This could be your new hobby.

If you make cool stuff, people will pass it on to your children’s children’s children and you won’t spend eternity as just an old picture on a lost thumb drive. We suggest: Making Poor Man’s Guitars, a 176-page paperback with detailed instructions for building string instruments out of cigar boxes, frying pans, tin cans, mailboxes and washtubs, with a beer-can microphone thrown in.

The Woodworker’s Shop Journal is a hardcover book with (100+) pages of 1/4" grids for project planning and sketches, plus (20+) pages of quick references, charts, lumber specs, tool guides, checklists and tips. Also a good place to keep passwords and other personal information because burglars are famous for not caring about carpentry skills.

A must-have for micro-warriors; Mini Weapons of Mass Destruction by John Austin (author of the best-selling Cubicle Warfare) is 241 pages of detailed instructions for building (42) implements of spitball warfare from ordinary household objects and office supplies. With the caveat that this is written for responsible individuals who take reasonable safety precautions (don't do anything your mother would scream at) we have to say that we love the binder-clip crossbow and the tongue-depressor catapult. Volume 2, which is 251 pages, has a secret-agent flair with new gadgets like the push-pin dart, toothpaste periscope and cereal briefcase. Volume 3, 267 pages, continues with a Medieval flavor and over a dozen catapults and ballistae, plus a buncha bows and crossbows. Oh, just buy the whole 3-volume Library of Destruction and get it over with.