At home
Parents and carers. When homework stalls on a word rather than a calculation, look it up together. You do not need to remember the maths yourself — the explanation is written for both of you.
Free · Open · No sign-in
Math Word Explorer
Word problems are often hard for a reason that has nothing to do with the maths. They are full of words like denominator, perimeter and regroup. This tool explains all 189 of those words, from Kindergarten to Grade 5, in plain language a child can read on their own.
Open the Explorer
Works on a tablet, laptop or phone. Nothing to install.
Why we made it
A child can know how to subtract and still be stuck on a problem, simply because they are not sure what how many are left is asking. The maths was never the barrier. The language was.
So every word here is written twice over. First as a short, plain definition. Then as a small story with a real situation — someone counting grapes, fencing a garden, sharing a pizza — because a word makes far more sense when you can picture it happening.
Every explanation is checked against the Flesch reading scale when the site is built, so the language stays within reach of the age it is written for instead of drifting upward over time.
What is inside
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Plain definitions
Every word said simply, in one or two short sentences.
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A worked example
A short story that shows the word doing its job in a real problem.
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Common mix-ups
The mistake children usually make with this word, named plainly.
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Read aloud
A button that speaks the word and its meaning for children still building reading fluency.
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A map of the words
A 3D map showing how each word sits inside its grade and its topic.
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Search everything
Look up any word across all six grades at once, by name or by meaning.
Who it is for
In the classroom
Teachers. Put it on the board when a new word comes up, or let children look words up themselves during independent work. Words are grouped by grade and by Common Core domain, so it lines up with what you are already teaching.
In tutoring
Tutors and support staff. Check quickly whether a child is stuck on the vocabulary or the method, and use the shared examples as a starting point for talking a problem through.
On their own
Children. Big buttons, read-aloud, and a tick beside every word already explored. Nothing to sign up for and no wrong turns to take.
No tracking. None.
This site collects no data at all — no sign-in, no analytics, no cookies, no advertising. Nothing about a child is sent anywhere or stored on any server. The only things saved are on your own device: which words have been opened, and whether sound is on.
Free to use and to build on
Made by the Usable Math team at the University of Massachusetts Amherst, with the Society & AI research group.
It is an Open Educational Resource under CC BY-NC 4.0, so you may share and adapt it for non-commercial use with credit. All of the code and the word bank are public at github.com/sai-educ/math-vocab.