Example:
Paragraph 1. Provide a brief background to establish context. (what’s known)
Paragraph 2. Identify knowledge gaps and constraints in previous research. (what’s unknown). Group similar studies and summarize at a high level. Refrain from incorporating intricate details, speculations, and criticisms of individual studies. If unsure, consider whether the information is essential to grasp your study question/aim or whether it would better suited for the Discussion.
Avoid needless repetition in the Introduction and Discussion; it wastes words and gives the impression that you had little to discuss and therefore used background material to fill space.
Paragraph 3. Provide a clear rationale for why you started the study and what new information it will reveal. (statement of purpose).
Example phrasing includes: “We hypothesized that”, “We aimed to”, “This paper describes,” “We asked whether”
Optional: Include one or two brief sentences about your experimental method. Explain how your study will fill the knowledge gaps and why your study matters. Do not describe methods, results, or conclusions. Note: some journals (though not common) may require you to summarize the main finding in the Introduction; always refer to specific guidelines or read a recent issue for example.