Measurement

We can compare the lengths of objects. A pencil is longer than a crayon. A crayon is shorter than a pencil. To compare: place both objects side by side, starting from the same end. The one that sticks out more is longer. Practice: Compare your hand with your friend's hand. Who has a longer hand?

Some objects weigh more (heavier) and some weigh less (lighter). A watermelon is heavier than a grape. A feather is lighter than a stone. We can feel weight by holding objects in our hands — two hands become a balance! The heavier side goes down, lighter side goes up.

A container can be full (no more can be added), half-full (half the space is used), or empty (nothing inside). A full glass of water spills if you add more. An empty glass can hold water. Half-full means exactly half is filled. Practice: Look at these jars and say if they are full, half-full, or empty.

Before rulers, people used body parts to measure: Cubit (elbow to fingertip), Handspan (thumb to little finger), Foot (length of foot), Pace (one step). Problem: these are different for everyone! That is why we need standard units (cm, m, kg, litre). Standard units are the same for everyone.