History of Science
Top Scientific Discoveries of the 18th Century, Ranked
November 4, 2026
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History of Science
Top Scientific Discoveries of the 18th Century, Ranked
November 4, 2026
Engineering
18 Facts About Robotics Engineering Most People Miss
November 4, 2026
Chemistry
Iron Compounds: Types, Colors, and Uses Explained
November 4, 2026
Computer Science
15 Examples of Machine Learning Models and What They Do
November 4, 2026
Before you buy
Books and gear for science readers, students and classrooms, with the specs and editions checked for every pick.
Free to print
Periodic tables, conversion charts and worksheets as free PDFs in US Letter and A4, with answer keys for the quizzes.
Weight Conversion Chart
Kilograms to pounds and pounds to kilograms for every body weight, plus ounces, grams and a units table.
Height Conversion Chart
Feet and inches to cm and cm to feet and inches, from 4 to 7 feet, with meters on every row.
Printable Periodic Table
Free periodic table PDFs in color, black and white, blank with a key, kids and an element list, plus a build-your-own customizer.
Fresh from the lab
Biology
33 Facts About Biomes (and Why Nobody Agrees on the Count)
A biome is a large region defined by its climate and the plants and animals that have adapted…
November 4, 2026
Geology
Minerals in Nevada: What’s Mined, What’s Collectible
TLDR Table of Contents Nevada’s official minerals in one place Silver is Nevada’s state mineral, and the state’s…
November 4, 2026
Chemistry
Uses of Calcium: In Your Body, Food, and Industry
The main uses of calcium are structural and electrical. In your body, calcium builds bones and teeth and…
November 4, 2026
Geography
Caves in Rhode Island: Where to Find Them (and Get In)
TLDR Table of Contents Caves in Rhode Island exist, but they are not the kind you’re picturing. There…
November 4, 2026
Chemistry
Examples of Synthetic Polymers and Their Everyday Uses
TLDR The most common synthetic polymers are polyethylene, polypropylene, PVC, polystyrene, PET (polyester), nylon, Teflon (PTFE), polyurethane, Kevlar,…
November 1, 2026
Travel
Science Museums in Washington, DC: Where to Go and When
“Washington” means two places, so first: this guide covers Washington, D.C. If you’re headed to Washington State, the…
November 1, 2026
Biology
Examples of Tissues in Animals and Plants
TLDR Animals have four tissue types. Epithelial tissue covers and lines (skin, stomach lining). Connective tissue supports and…
November 1, 2026
Biology
18 Facts About Regenerative Medicine, Minus the Hype
Regenerative medicine is the set of techniques that repair, replace, or regrow damaged cells, tissues, and organs instead…
November 1, 2026
Chemistry
Uses of Uranium: From Power Plants to Vintage Glass
TLDR Table of contents One element, three versions Almost every question about what uranium is used for comes…
November 1, 2026
Why we publish
33Science is an independent publication exploring the natural world — from the chemistry of a single crystal to the life cycle of a star. Clear, curious and rigorously sourced, for readers of every background.
