You can do Monsky Monsky's theorem, that a square can not cannot be divided into an odd number of equal area triangles. On the way you will have to do
- p-adic numbers,
- Sperner's lemma,
- present $\mathbb{R}$ as a vector space over $\mathbb{Q}$.
In case if you have more time, you could
- use Sperner's lemma to prove Brauwer's Brouwer's fixed point theorem.
- use (3) to do Dehn Invariants
- and I am sure you can find what to do with p-adic numbers

