length & distance

The length is the size between two things, using various units.

eg the length of the swimming pool.

eg the length of time between Period 1 and Period 2.

The distance is the length between two things in units such as centimetres (cm), metres (m) , kilometre (km), etc.

eg the length of the swimming pool (in metres).

eg the distance between Auckland and Wellington (in kilometres).

The standard measurement of distance in the metric system is the metre. 

A metre = 100cm or 1,000mm

In Mathematics, length is often used to mean the distance of a side of an object, usually horizontally and the longer side.

The width of an object is the distance of a side of an object, usually vertically and the shorter side.

The base of an object is the distance of the side along the 'bottom of the shape' or 'at the ground'. 

The height of an object is the distance from the base of an object to the top. Sometimes this is called altitude. 

It is also considered to be the distance from the lowest point of the object to the highest point of the object.

eg the height of the rectangle

eg the height of the cylinder

Note: People may use length and width or base and height for 2-dimensional (2D) shapes.

In 3-dimensional (3D) shapes, the depth is sometimes used to describe the third dimension.