Activities/Ruler
Where to get Ruler
About Ruler
Ruler is a simple collection of measurement tools that are displayed on the screen.
CM and MM scales
CM and MM grid
angles
checkerboard
Since the OLPC XO computer has a 200 DPI display, the rulers are quite accurate. One other hardware, where the display resolution is not known, their is a spinner to let the user set the DPI. Ruler saves this value to the Journal, so it need not be set on subsequent uses of the Activity.