A polynomial is a sum of terms, each a number times a power of x. Algebra tiles make it visible: an x² square, x strips and unit squares. Adding, subtracting or multiplying two polynomials always gives another polynomial, just as adding, subtracting or multiplying whole numbers always gives a whole number. The area model turns (x + 2)(x + 3) into x² + 5x + 6, and seeing the structure of an expression, a square of a binomial or a difference of squares, lets you rewrite it.