Adult Sheldon: The next day, Dr. Linkletter ran his experiment. I'm proud to say I never broke my word, and he eventually figured out the problem. [flames wooshing]
Dr. Linkletter: Fire! Fire! Fire! Was it too much oxygen in the reagents?
Sheldon: See? You didn't need my help after all.

Principal Petersen: Our next young speaker needs no introduction, but that didn't stop him from writing one and making me read it. [laughter] "Fun fact." [audience groans, murmurs] I hear you. "The word 'valedictorian' is from the Latin 'valedicere,' meaning 'to say farewell.' It is primarily used in the United States, Canada, the Philippines and Armenia." Maybe that fact's more fun in Armenia. Please welcome your valedictorian, Sheldon Cooper.
Mary: Yay, Shelly!
Sheldon: Hello. I'm not very comfortable speaking in front of crowds. But there's a technique to reduce stage fright by focusing on one person in the audience and delivering your speech just to them. That's what I'll be doing today. If it weren't for this person, I wouldn't be here right now. They've taught me a lot, and it's by their example that I found the courage to move forward into this new and exciting chapter of my life. Missy... ...this is for you. Change can be scary, but I know we're going to be fine... ...because like you said, "It's okay to be scared. We just have to do it anyway." So if any of my fellow graduates are nervous about the future, know that you're not alone. I suggest you all try to be as brave as my twin sister. That's my plan. Missy, I wish I could give you advice about middle school, but I was so smart, I skipped it. If you make it to high school, we'll talk. Thank you. [applause]

Missy: What's it like to not believe in God?
Sheldon: It's great. Big fan.
Missy: Are you ever afraid you're wrong?
Sheldon: About religion? Never. About other things? Also never.

Ms. MacElroy: Now, can anyone tell me why Melville shifts the narrative voice from Ishmael to Ahab? [Ms. MacElroy waits for somebody else to raise their hand] Sheldon.
Sheldon: I have a tummyache. I'd like to see the nurse.
Derek: A "tummyache"?
Sheldon: Yes, Derek, I have a tummy and it aches. Ergo, tummyache.
Derek: Ergo?
Sheldon: It's Latin, Derek.
Ms. MacElroy: Go to the nurse.
Sheldon: And to answer your question, the shifting point of view grants the reader a broader perspective of events than typically allowed by first-person narration.
Ms. MacElroy: Where were we?
Sheldon: And "ergo" is Latin for "hence," Derek.

George Jr.: What is this?
Meemaw: That's the exercise guy Meemaw likes.
George Jr.: I can't believe anyone pays money to watch old people sweat.
Missy: 40 bucks?
George Jr.: They sold over a million of those? At 40 bucks a pop? Do you know how much money that must be?
Missy: I'm not a calculator.
[later:]
George Jr.: 40 times... one million. That's 40 million!
Missy: Whoa.

Adult Sheldon: Behind every great scientist, there were often unsung helpers toiling away in the background. Presenting... "Great Lab Assistants in Scientific History" When Alexander Graham Bell needed an assistant, it was Thomas Augustus Watson who answered the call. [laughs] Get it? "The call". [snickers] Madame Curie's daughter Irène was also her lab assistant. Irène was so dedicated, she died of radiation poisoning. Unlike her sister Ève, who selfishly lived to 102. Lastly, Émile Roux was assistant to Louis Pasteur. When they worked on the rabies vaccine, Roux kept a loaded gun in the lab to shoot Pasteur in the head if he got infected. He never had to, but it's fun to know he would have.
Dr. Linkletter: No, Sheldon. You can't be my lab assistant.
Sheldon: Maybe you weren't paying attention. I'll start over. Behind every great scientist, there was a dedicated as...

Adult Sheldon: While not the lab work I hoped to be doing, it did feel good to be part of an actual experiment. A tedious, menial part that could be performed by a monkey. Or worse, an engineer.