The problem
One paragraph: our two best theories disagree, and where that matters. 800 to 1000 words in total, from your script, at the level of the talk: engaging, not technical.
What General Relativity gets right
A paragraph or two.
What Quantum Mechanics gets right
A paragraph or two.
Where they collide
Gravity across the two theories, as in the talk.
The bridges
The ideas the talk mentioned, including String Theory and a Theory of Everything.
Why I cared
Why a 15-year-old picked this. No hedging about being young.
Since the talk
Anything you’ve learned since, or would change now.
Reading
Only things you actually read: title, author, and a link where there is one.