The monomial and its standard form
An expression that is a product of numbers and letters (and their natural powers) is called a monomial; for example, 3ab, -4a · 3ab, c⁵, 7 and a are all monomials. Factors written with digits are numerical factors and factors written with letters are letter factors. A monomial is in standard form when it has one numerical factor in the first place followed by powers of different letters. To bring a monomial to standard form we multiply all numerical factors and write the result first, and combine equal letters into powers. The numerical factor of a monomial in standard form is called its coefficient: it is 6 in 6ab², 1 in abc², and -1 in -abc. To find the value of a monomial it is convenient to bring it to standard form first.
“Monomial builders”: cards carry numbers and letters. A group builds a monomial, writes it in standard form and names its coefficient. Another group looks for mistakes.