Kill the Enderdragon.

Play for 100 days.

Find an underwater ruin.

Create an Iron Golem.

Travel by minecart to a point at least 500m in a single direction from where you started.

Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Deal nine hearts of damage in a single hit.

Destroy a Ghast with a fireball.

Construct a Dispenser.

Build some bookshelves to improve your enchantment table.

Construct a Nether Portal.

Throw diamonds at another player.

Smelt wood trunks using charcoal to make more charcoal.