Most first-year algebra curricula contain a unit on graphing on the Cartesian coordinate plane. Many students intially have some difficulty grasping the concept of representing algebraic equations visually, as it’s a real paradigm shift from traditional arithmetic. Graphing calculators, both hardware and software, are helpful tools in the teaching process, as they allow learners to quickly and efficiently experiment with plotting equations, so they can understand how changes made in an equation affect the shape of the graph.

In this section, we’ll use HTML5 Canvas to implement a very basic graphing calculator for simple linear equations that can be embedded in algebra ebooks. Figure 1-2 displays the graphing calculator interface we’ll create: a two-dimensional coordinate plane with x- and y-axes marked in red, and a set of buttons below for graphing linear equations on the grid.