FIGURE 8.14 The number-line task and typical developmental changes on it (a) On each trial with a 0–100 number line, children need to estimate a different number’s location on the line. (b) Kindergartners’ median estimates for each number on the 0–100 number-line task increased with the number being estimated, but in a way that involved overestimates of relatively small numbers and underestimates of large ones, as with a logarithmic function. (c) Second-graders’ median estimates for each number on the same task increased linearly with the size of the number being estimated, and were quite accurate. (Data from Siegler & Booth, 2004)