Learn Spanish (Latin America): Ella considera la idea de viajar. - She is considering the idea of traveling.

Yes, considerar is a verb of thinking and works exactly like creer or pensar. If the sentence used que (that), the affirmative would take the indicative (Ella considera que es buena idea) and the negative would trigger the subjunctive (Ella no considera que sea buena idea). However, in this specific sentence, there is no que clause at all—she is simply interacting with a noun (la idea), so those rules don't apply here.

Could I skip la idea de and just say Ella considera viajar?

Absolutely! Just like in English ("She is considering traveling"), you can place the infinitive verb viajar directly after the main verb. Saying Ella considera la idea de viajar just slightly emphasizes "the idea of traveling" rather than the action itself.

Why do we need the preposition de before viajar?

In Spanish, when you use a noun (like idea) and immediately follow it with a verb to explain what the noun is about, you must connect them with de. It matches the English structure directly: "the idea of traveling."

The English translation says "traveling". Why doesn't the Spanish sentence use the -ndo form (viajando)?