Common uses of 'period'

Period can be used as a noun to refer to a specific length of time. It is often used in expressions such as over a period, during a period and a period of time. We’ll observe the patient’s weight for a period of three months. During this period, we normally get a lot of rain. Period can also be used to talk about a time in a person’s life or in history. It often has an adjective in front of it. I went through a difficult period when I returned to the UK. The Elizabethan period was famous for its playwrights such as Shakespeare. In school, we can use period to refer to a part of a day when a specific subject is taught. I have maths in the second period on Tuesday. Mrs Jackson takes us for art in the last period on a Friday. Period in American English refers to the punctuation mark which shows the end of a sentence. In British English we refer to this as a ’full-stop’. Is that a period or a comma? Some writers need to use more periods in their paragraphs as their sentences are too long.