Create your own centimeter ruler. Then, estimate and measure with lengths with it. Warm up with a Mystery Math Mistake as you add two 2-digit numbers using a decomposition strategy.

It’s meant for measuring objects and that’s exactly what it does. When you need to measure something ‘in a pinch’, Ruler App is there. The makers of Ruler 2 are also having a contest - “In celebration ...

How to Change Ruler Units in GIMP. The GIMP graphics editing program places a ruler above and to the left of the images you are working on. You can use these rulers to measure parts of your image ...