An introduction is like a guidebook to your whole assignment. It gives background information into your topic area and outlines all the ideas you are going to present. Remember that most introductions will be about 10% of the final essay and will include some or all of the following:
Look at the other paragraphs in your essay. Paragraphs should all be of roughly similar length. If you find that you have one or two paragraphs that are much longer than all the others, read them carefully and try to find out why.
Writing and the dread five-paragraph essay | Darwin's …
If a paragraph is too short, it may be because the initial idea has not been developed sufficiently. To some extent, the level of development is dependent on the writer's purpose and the overall length of the essay. However, you should beware of paragraphs of only two or three sentences. Read them carefully and consider if your idea has been sufficiently developed.