Flickr has updated their search function as well (Thank you Mashable). They’ve also add the ability to search for Creative Commons under the Advanced Search link. For most of the searches in languages, you’re probably best off searching by Tag. You’ll see this option under the Advanced Search as well. Use the target language for your class instead of English to find more culturally appropriate photos.
Keep in mind as well that many images in Flick are geo-tagged, which means you narrow your search by location as well. Do this from the main page and under the Search dropdown, choose Location.