12 terms

addends

numbers added in an addition problem

algorithm

any process for solving a mathematical problem

commutative property of addition

changing the order of addends does not change their sum (a + b = b + a)

identity property of addition

the sum of any number and 0 is equal to the initial number (a + 0 = a)

sum

the result of addition

ordinal numbers

numbers that describe position or order (first, second . . .)

difference

the result of subtraction

fact family

a group of three numbers related by addition & subtraction or by multiplication & division

inverse operations

operations that "undo" one another

equation

a number sentence that uses the symbol = to show that two quantities are equal

minuend

the top (or largest) number in a subtraction problem

subtrahend

the bottom (or smaller) number in a subtraction problem