Enter an End Portal.

Relieve a Blaze of its rod.

Acquire diamonds with your iron tools.

Construct a Nether Portal.

Construct one type of each tool (one pickaxe, one spade, one axe and one hoe).

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

Attack and destroy a monster.

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

Construct a better pickaxe.

Turn wheat into bread.

Smelt an iron ingot.

Use planks and sticks to make a pickaxe.

Punch a tree until the block of wood pops out.