My wife and I lived in Spain teaching English for part of 2017, and made a combined income of about $9,000 during our time there. Do we have to pay tax on this income?

We both worked as ESL teachers for companies that pay taxes in Spain, but the companies do not provide a W-2 as they are based in Spain. We moved back to the US in July 2017, her total US income was $8,500 and I didn't start working until 2018. How do I declare these funds on my return, and is there a way to avoid having to pay on the $9,000 earned in Spain?