If you use Chrome as your browser, you could kill two birds with one stone and learn a language while perusing your favourite websites.
Flewent is a plugin for Chrome that will translate words on a webpage into a different language, meaning you can pick up new words in your target language as you read. This only works for English-language sites, and not all languages are included – it lists Chinese and Japanese functionality as ‘experimental’ for example.
You can control how much of the page you want translated by setting a percentage – and if you don’t know the word, you can hover over it for the English translation. The translation may not be perfect as it uses Google Translate, but you should be able to get a reasonable idea from the sentence context anyway.
This seems like a great way to learn new vocabulary in your target language whilst doing something you’d do anyway – browse the web. So after you’ve taken your German lessons in Washington, you can go home, relax and pick up some more vocab!