Which way should your number line go?

<p dir="ltr">In classrooms where children learn mathematics, one of the things you’re sure to see somewhere is a number line. But these number lines can vary quite a bit from one to another – and one difference is which direction the number line goes. Are your number lines horizontal or vertical? Does it matter? We think that we see horizontal number lines much more often than vertical ones. Perhaps that’s simply because we read and write from left to right, which makes it easier for books or worksheets to format them that way round. In fact, reading direction seems to have profound effects on children. Children’s early experiences seeing writing going left to right in western cultures seem to create a bias towards a horizontally (left-to-right) oriented number line, even before they start reading and writing themselves (Göbel et al., 2018). (Cont.)