I'd like to share a Scratch project, 2D Grid Drawer. This is a simple project but is very helpful to demonstrate graphing equations. The default granularity is 20 (in Scratch coordinate system). It can be changed by changing the "add" variable of the "pen" sprite. After changing the "add" value, just click the green flag to redraw.
The cool thing about this project is that you can capture the grid on the stage and turn it to the stage background. Once a stage has such grid background, you can add objects to the background using Scratch’s motion tools such as “go to x =? “ block.
To save the grid on the stage, right click the stage, and select “save picture of stage” from the pop-up menu and save it to a file.
To use this image as the background in a new project, just import it as the stage’s background (you can do so by opening the Stage sprite's background editor.
Here is a list of download links
grid drawer project - the project that draws the grid
20-granularity grid - empty project with 20-granularity grid background
40-granularity grid - empty project with 40-granularity grid background
