Rulers

When we want to know how tall something is or how far something has travelled, we normally use standard units of measurement such as centimetres. To compare two heights or measurements, we don’t need to use any specific unit of measurement and can instead make our own. This is what some children decided to do. In the image below, we can see a child being measured against a scale of numbers that the children devised themselves.

In the image below, some children have made their own rulers (using their own units, i.e. not centimetres). The children went on to measure objects around the classroom and the distances travelled by toy cars.

Some units of measurement can be better suited to one task than another. If we were thinking about how far a toy car had travelled, centimetres might be appropriate; however, if we wanted to measure how far a real car had travelled, kilometres might be more sensible. These are formal units of measurement, but the same idea holds with more unusual units. In the toy car example, pen lids are probably going to be more suitable than shoes, as they are smaller, so we will not have to use half units so much.

We can describe the dimensions of objects using many different units of measurement. For example, the length of a sofa in cushions, compared to the length of the same sofa in books. The image below shows a visualisation of this.

It could be a fun activity for children to choose different units of measurement and compare the relative lengths of items around the classroom. Children could also combine objects to form a measuring system, for example, a piece of paper could be one straw and three marbles long.