When you write instructions, remember to check that you have used the correct punctuation. Don't forget to start your sentences with a capital letter and end them with a full stop. Glue the wall of your model together.

Do you need a full stop at the end of a paragraph?

Leaving it off on headlines and titles is fine. But otherwise, it's not optional. Periods belong at the end of sentences, and since paragraphs are made up of sentences, they get a full stop/period at the end, too. Readers should not be left hanging, wondering if something is missing.

When should full stops be used?

A full stop should always be used to end a sentence. The full stop indicates that a point has been made and that you are about to move on to further explanations or a related point.