Why a number line, and why past 1?

"Where does 5/4 go?" is a different question from "shade 5/4 of a pizza" — and research says it's the more powerful one. Placing fractions on a number line trains students to treat a fraction as one number with a size, not as two whole numbers stacked on top of each other. That misreading — whole-number bias, where 1/8 looks bigger than 1/4 because 8 beats 2 — is one of the most persistent errors in elementary math (Ni & Zhou; Braithwaite & Siegler). Number-line placement with immediate feedback is the fraction intervention with the strongest evidence behind it (Siegler and colleagues), and fraction magnitude knowledge predicts later algebra success. This tool defaults to lines that run past 1, because fractions greater than one whole are the fastest way out of the "a fraction is a piece of one pizza" trap. Flash a fraction, let the class argue about where it lives, then reveal the partitions and count the unit fractions together.