Adding with number lines

A number line shows addition as movement — starting at a position and moving right — which connects addition to the sequential nature of the number system.

It builds the 'count on' strategy: students start at the larger addend on the line and jump forward by the smaller addend rather than counting both groups from zero.

Common errors include starting from zero instead of the first addend, or counting the starting position as one of the jumps — both corrected through teacher modeling.