Children should be encouraged to estimate and to develop the skills of using the units properly. Some care as suggested below need to be taken to enable the children to learn using the scale correctly: Familiarizing children with the marking of sub-units on the scale: They need to be clear about the division marked on the scale at equal distances. On a meter scale, to begin with, they should be able to identify the centimetre marks. After they become familiar with using centimetre in measuring length, they may be introduced to meter and millimetre. Appropriately placing the scale with the object of measurement: Placing the scale correctly and closely alongside the object to be measured is very important. Estimating the length before exactly determining it: Always encourage children to estimate the length of the object being measured before going to determine the exact length of the object using the standard scale. Correctly calculating the length: The children should be led through several instances of measuring different objects with a ruler or a scale to determine the exact length of the object they are measuring. Developing the measuring skills: Measuring with a standard scale requires some basic skills like alignment of the scale with the object, taking correct readings and calculating the differences of readings. None of these is a difficult skill to acquire, but children very often commit mistakes due to sheer carelessness. Taking care at the early stage would help the children in developing these skills with ease. Choosing an appropriate ruler or scale: Scales of different lengths and forms are available in the market. Scales of 1meter, 30 centimetre and 15-centimetre lengths are commonly available and used in the schools. Besides, children may be exposed to measuring tapes of different lengths used by carpenters and masons, iron rods used in measuring clothes in shops and such other scales. Hence, we conclude that all the above points are correct.