AI Tutor
Imagine a detective walking into a courtroom, pointing at a suspect, and yelling, "He's guilty!"—without showing a single fingerprint, photo, or clue.
In reading and writing, stating an answer without proof is just as useless; you need textual evidence to back up what you say.
How do we turn a raw piece of text into an airtight explanation that convinces anyone?

The CER Framework

To build an explanation, we use a three-step formula called CER: Claim, Evidence, and Reasoning.
A claim answers the question, evidence provides the exact facts or quotes from the text, and reasoning explains how that evidence proves your claim.
What does this look like with a real informational text? Let's look at an excerpt about deep-ocean ecosystems.

The Source Text

"Deep-sea hydrothermal vents spew superheated mineral water into pitch-black ocean trenches. Despite zero sunlight, giant tube worms thrive here by hosting bacteria that convert toxic hydrogen sulfide into organic energy through chemosynthesis."
Now suppose a question asks: How do animals survive around hydrothermal vents without sunlight?

Building the Explanation