Either a ruler or a scale.
You should use the "math book" to look up the answer to this question as opposed to just having someone answer it on this website.
The best unit is a litre.
Unit of Measurement used when measuring Weight or Mass
The best unit for measuring the length of a pencil is inches.
Gram
centimetres
inch
pounds
A millimetre.
kilograms
For a desk like one used in schools the best unit would be pounds. Good luck on your measuring!
The best unit of measure to use when measuring the amount of water in a drinking glass is ounces. A liquid measuring cup can be used to measure the ounces of water.