Medicine
Medical Devices: What Counts and How They’re Classified
November 5, 2026
Search
Medicine
Medical Devices: What Counts and How They’re Classified
November 5, 2026
Geography
Natural Resources of England: What It Has and Where
November 5, 2026
Physics
15 Examples of Elastic Potential Energy (With Numbers)
November 5, 2026
Science History
25 Scientists Born in Italy and What They Discovered
November 5, 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
Chemistry
Examples of Esters: Smells, Uses, and Formulas
An ester is an organic compound with the group RCOOR’, a carbonyl carbon (C=O) bonded to an oxygen…
November 5, 2026
Earth Science
Active Volcanoes in Wyoming: Yellowstone and Beyond
Table of Contents TLDR No volcano in Wyoming is erupting, and none is expected to soon. Yellowstone is…
November 5, 2026
Physics
30 Facts About Physics (and Why They’re True)
Most lists of physics facts hand you a claim and move on. “Time stops at light speed!” Sounds…
November 5, 2026
Science History
1983 Nobel Prize Winners: All Six Laureates and Their Work
Table of Contents TLDR: the 1983 winners at a glance The 1983 Nobel Prize winners were Subrahmanyan Chandrasekhar…
November 5, 2026
Measurement
Imperial Units: Complete Chart and Metric Conversions
Imperial units are the system of measurement Britain standardized in the Weights and Measures Act of 1824: inches,…
November 4, 2026
History of Science
Top Scientific Discoveries of the 18th Century, Ranked
Most lists of 18th century science give you Franklin’s kite, oxygen, and Uranus, then run out of ideas.…
November 4, 2026
Engineering
18 Facts About Robotics Engineering Most People Miss
Robotics engineering is the field that combines mechanical engineering (the body), electrical engineering (the nerves and muscles), and…
November 4, 2026
Chemistry
Iron Compounds: Types, Colors, and Uses Explained
Iron compounds are substances in which iron is chemically bonded to one or more other elements, and nearly…
November 4, 2026
Computer Science
15 Examples of Machine Learning Models and What They Do
Most lists of machine learning models read like a glossary: a name, a vague sentence, on to the…
November 4, 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.
