This e-book is the fourth in the Plain Language series. It focuses on the measurement topic. The e-book takes the maths (algebra) from books 2 and 3 and shows how it is relevant when maths is applied in practical settings. Being written in plain language, and progressing in small steps, it is easy to follow. It has been developed from my classroom teaching notes. The content is a specifically structured to overcome problems that students commonly encounter when learning mathematics. This makes it a good resource for teachers who want additional material in order to broaden the student's awareness of maths. Parents have found it helpful in providing a basis for discussion when they want to assist their children.