Glossary
Every term used on this site, defined plainly, with the colour it wears on the board. No jargon explaining jargon.
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Terms
12 terms
Variable
A letter that holds a number you do not know yet. A placeholder, not a mystery.
3x + 7
Expression
A math phrase with no equals sign. Something to read, not something to balance.
3x + 7
Equation
A claim that two expressions are equal. Because it is a claim, you can check it — and balance it.
3x + 7 = 22
Term
One piece of an expression, separated from the others by + or −.
3x, 7, −5y
Coefficient
The number multiplying a variable. It tells you how many of that variable you have.
3 in 3x
Constant
A term with no variable attached. Its value never changes.
7 in 3x + 7
Like terms
Terms with the exact same variable part. Only like terms can be combined.
3x and 5x
Substitution
Replacing a variable with a specific number, without changing the operation around it.
x = 4 → 3(4) + 7
Distributive property
Multiplying a number across everything inside parentheses.
2(x + 4) = 2x + 8
Order of operations
The fixed order for working an expression: parentheses, exponents, multiply/divide, add/subtract.
2 + 3 × 4 = 14
Inequality
A claim that one expression is greater than, less than, or not equal to another. Its answer is a range.
x + 3 > 10
Final Unlock
The optional hardest problem at the end of a Mission. Skipping it costs nothing.
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