"Then I'd be hooked." "What's—?" "Like stuck on a hook, because I'd need [painkillers] all the time." (1.86-1.88)
Ma has to explain almost everything to Jack. He's only five. She has a great ability to explain the idioms that people use all the time without thinking. And she has incredible patience since she's able to define all of these things for her son so many times a day.
I know that already, everything's breakable. (1.552)
This is a pretty profound line from a five-year-old. Most kids don't learn to take care of their things for a very, very long time. Jack has learned this lesson pretty early.
"Listen. What we see on TV is… it's pictures of real things." That's the most astonishing I ever heard. (1.101-1.102)
Revealing to Jack that TV is kind of real opens up a whole new world for Jack to learn about. This revelation changes Jack's entire world, making him think about everything in a whole new way.
I'd love to watch TV all the time but it rots our brains. (1.100)
Ma uses TV mostly to educate Jack, watching educational shows like Dora and playing the Parrot game—in which Jack repeats back what people say—to build his vocabulary. She limits the use of TV, though, because most TV isn't educational at all, especially not to a five-year-old.
Sometimes I forget things. Ma tells me and I remember them after that. (1.161)
Ma is pretty patient, but Jack is patient, too. Even at a young age, he realizes that he sometimes forgets things, but this doesn't frustrate him. He just knows he has to be reminded of things, and everything will be okay.
Part 2: Unlying
Alice says she can't explain herself because she's not herself, she knows who she was this
morning but she's changed several times since then. (2.116)
Jack is talking about Alice in Wonderland here, and he's relating it to himself. When Jack's view of the world changes because of new knowledge, he changes right along with it. His identity, especially at such a young age, is closely tied together with how he sees the world, and how he thinks he fits in it.
Stories are a different kind of true. (2.271)
Lots of the "stories" Ma tells Jack, like How the Berlin Wall Fell Down and Princess Diana are stories of actual events. Even the fairytales, like the mermaid who has a child in captivity, are allegories. Is there anything allegorical about Room itself?
"I wouldn't lie to you about this," Ma says while I'm slurping the juice. "I couldn't tell you before, because you were too small to understand, so I guess I was sort of lying to you then. But now you're five, I think you can understand." (2.533)
Ma knows that Jack is much wiser than your average five-year-old. His curiosity and passion for knowledge make it easier for him to understand complicated concepts. Ma is confident he'll eventually get them, which is why she shares so much with him, without sugarcoating things, as he gets older.
Part 3: Dying
Before I didn't even know to be mad that we can't open Door, my head was too small to have Outside in it. When I was a little kid I thought like a little kid, but now I'm five I know everything. (3.20)
The more knowledge Jack gets, the more he thinks he knows everything. He doesn't yet have the knowledge to know that he will never know everything.
Part 4: After
"I don't want there to be bad stories and me not know them." (4.1051)
Jack wants to know everything, and we mean everything, even if it makes him feel uncomfortable, scared, or weird. That's pretty ambitious for someone of any age.