To measure a physical quantity such as length, mass, time, current, we use an instrument such as a metre scale or vernier callipers for length, a balance for mass, a stop watch for time, an ammeter for current. These measurement are done with the help of a scale. Learn what is the minimum scale of each instrument and find out their least count. The least count of an instrument is the smallest measurement that can be taken accurately with it. e.g. least count of a stop watch is 0.5 second.
Learn the principle of vernier calliper and screw gauge and find out the possible errors done by a user while taking any measurement, also find how to take accurate readings.
Learn about significant digits used in measurements and calculate different types of errors. The significant figures are the number of digits used to express the measurement of the physical quantity such that last digit in it is doubtful and rest all digits are accurate. e.g Reading 1.2 has two significant figures which are 1 and 2 ,where 1 is fully reliable while the second digit is uncertain.
A SmartTest on Measurement of Length, Volume, Time and Mass
Learnhive Lesson on Measurement of Length, Volume, Mass and Density