1. Assertion, Evidence, Commentary
APA Style

2. Assertion
Perhaps two or three per subheading in the paper
Each may be the topic sentence of a paragraph
Answers the guiding question
Big Cats Lions are the biggest cat species. [paragraph here] Tigers are the most popular big cats. [paragraph here] Cheetahs are the fastest runners in the world.

3. I’m stating a fact here and I will prove it.

4. Evidence
Used to back up your assertion
Paraphrased or directly quoted from your sources
Whether directly quoted or paraphrased, IT NEEDS TO BE CITED!
Big Cats Lions are the biggest cat species. Bob Smith the scientist says so in an article (Smith, 2014). Long-time zookeeper Suzie Jones agrees (2000), saying. “Lions are absolutely without question the biggest cats in the world.” Another wildlife expert, writes that male lions are usually 25 percent bigger than any other big cat (Snodgrass, 1999).

5. Here are three qualified sources who agree with what I just said
Here are three qualified sources who agree with what I just said. (I will cite them here and on the Reference page.)
Sally Snodgrass
Bob Smith
Suzie Jones

6. Commentary
Connects the evidence to the assertion
Explains why the evidence is significant and effective in conveying your idea
Big Cats Lions are the biggest cat species. Bob Smith the scientist says so in an article (Smith, 2014). Long-time zookeeper Suzie Jones agrees (2000), saying. “Lions are absolutely without question the biggest cats in the world.” Another wildlife expert, writes that male lions are usually 25 percent bigger than any other big cat (Snodgrass, 1999). If a male lion stood side by side with any other large cat, it is clear that the other cat would look quite small by comparison.

7. Now I will sum up my assertion and evidence…and transition to the next paragraph.

8. Lions are the biggest cat species
Lions are the biggest cat species. Bob Smith the scientist says so in an article (Smith, 2014). Long-time zookeeper Suzie Jones agrees (2000), saying. “Lions are absolutely without question the biggest cats in the world.” Another wildlife expert, writes that male lions are usually 25 percent bigger than any other big cat (Snodgrass, 1999). If a male lion stood side by side with any other large cat, it is clear that the other cat would look quite small by comparison.
Although lions are the largest cat species, tigers are the most popular big cats.