Tropecé con el último escalón al bajar las escaleras.

I tripped on the last step while going down the stairs.

Breakdown of Tropecé con el último escalón al bajar las escaleras.

• yo: I
• al: when
• la escalera: the staircase
• último: last

Questions & Answers about Tropecé con el último escalón al bajar las escaleras.

Why is it tropecé and not tropezé?

Because the verb is tropezar and it has a spelling change in the yo form of the preterite:

• tropezar → tropecé

This happens because Spanish changes z to c before e to keep the same sound.

Similar examples:

• empezar → empecé
• almorzar → almorcé
• cruzar → crucé

So tropecé means I tripped.

Why is there no subject pronoun like yo?

Spanish often leaves out subject pronouns when the verb ending already makes the subject clear.

• tropecé = I tripped

The ending -é tells you it is yo in the preterite.
You could say Yo tropecé, but it is usually unnecessary unless you want emphasis or contrast.

What does tropezar con mean exactly, and why is con used?