Mnemonic Devices: What They Are and How to Use Them in Math and Science

What is a mnemonic device?

The word comes from the Greek root for memory, and that's exactly what a mnemonic device is: a shortcut that makes an otherwise forgettable list stick. Instead of memorizing eight unrelated planet names in order, a student memorizes one easy sentence where the first letters line up. The sentence is forgettable in a different way, in a good way, it's silly enough to stay in your head.

The main types of mnemonic devices

• Acronyms turn the first letter of each item into a new word, like HOMES for the Great Lakes or ROYGBIV for the color spectrum.
• Acrostics build a full sentence where each word's first letter stands for something, like "Please Excuse My Dear Aunt Sally" for order of operations.
• Rhymes and songs use rhythm to make information stick, the same way a jingle gets stuck in your head.
• The method of loci attaches items to a familiar physical path, like rooms in your house, so you "walk through" the list to recall it.
• Visualization turns abstract information into a mental picture.
• Chunking breaks a long string, like a phone number, into smaller, easier-to-hold groups.

Mnemonic devices for math

• PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction) keeps order of operations straight.
• SOH CAH TOA ties sine, cosine, and tangent to their ratios: opposite/hypotenuse, adjacent/hypotenuse, opposite/adjacent.
• Simple rules for signs, like "same signs add and keep, different signs subtract," help with positive and negative number operations.
• A classic sentence where each word's letter count spells out the first digits of pi is a fun way to memorize an otherwise endless number.

Mnemonic devices for science

• Taxonomy order (Kingdom, Phylum, Class, Order, Family, Genus, Species) is commonly remembered through a silly sentence where each word's first letter matches.
• Planet order from the sun outward is one of the most common acrostic uses in middle school science.
• Mitosis phases (Interphase, Prophase, Metaphase, Anaphase, Telophase) can be shortened to an easy-to-say acronym.
• The electromagnetic spectrum, in order of increasing frequency, has its own acrostic shortcuts for students who need to recall the sequence on a test.

How to build your own mnemonic device

The best mnemonics are personal. A phrase a tutor finds memorable might not stick for your student, and a slightly inappropriate or extremely weird sentence is often more memorable than a polished one, because strange things stick better than ordinary ones. Start with the first letter of each item, play with word order until a sentence or acronym feels natural to say out loud, and test it a day later. If it's still there, it works.

What mnemonics can't do

A mnemonic helps you recall a list. It doesn't teach you why the order of operations works, or why mitosis happens in that sequence. Students who lean on mnemonics without building real understanding sometimes do fine on a straightforward recall question and then struggle the moment a problem asks them to apply the concept in a new way. Use mnemonics to lock in the sequence, and use practice problems to lock in the understanding.