Variable - a letter that represents an unknown number.
eg : x, A, n
Expressions - any single number or variable, or combination of operations ( +, -, x, / ) involving numbers. eg : 5, r, 8t, x+9, 2y, -7
Value - a known or calculated amount
Constant - a number that does not change. Increase or decrease that value of an expression.
Numerical Coefficient - a number that multiples the variable

Linear Relation - a pattern made by two sets of numbers that results in points along a straight line on a coordinate grid
eg :

Graph - a visual way to show how two sets of numbers relate to each other
Relationship - a pattern formed by two sets of numbers
Math game on graphing linear relations
Video :