There are times, especially when you are in competition where you will need to measure your robot's position. Without a ruler and a few beams, pins, and fancy pieces, you can create an effective tool.
Look at the following.
This is a leveler. The middle hanging piece will allow one to measure slope. But this is an extension of the measuring tool later shown on this page.
At an angle, slope, you can see the middle piece remains pointing downward. It uses gravity to hold its position. You can test a floor to see if there are bumps. Or, you can test a table to see if it is leveled.
Can you see, above, the measuring tool stretched out? It has 3 of the longest beams, 4 pins, and 2 "L" pieces. The "L" pieces are used to help measure out angles by matching holes.
This is showing that the angles of both beams, measured to the middle beam, are 90 degrees.
Matching holes from the "L" to the middle beam allowed for a measured angle that is almost 30 degrees.
This is almost 60 degrees.
Close to 80 degrees.
This is 90 degrees.
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Lets say you want to measure a turn. You could use this method at your own school and not at competition, but you can use the above tool. You would use the below protractor and use the tool above by matching angles you normally use. Once you get to know the holes and angles, you'll be able to use this at the competition table knowing that a certain match of the "L", matching holes, to the middle beam will be approximately a particular angle. This will help measure turns as well.
Make sure you use the motor reading in "View" on your NXT to help you measure.