Do a traditional lecture on the topic.
Assign standard homework. But for each question, ask where and how students arrived at their answers.
You can hope all you want that students will learn the material by attending your lectures, reading things you've assigned them to read, and getting a broad background on the topic from which they can draw to answer specific questions. But this is a day and age where they will just copy/paste the entire question into a search engine (including any misspellings). And there are lots and lots of people on the Internet who will happily write a direct answer to it if enough students input the exact same one. Yay for SEO longtails and ad revenue share.
Do a second lecture about all the online sources on the topic that students have found. "This one is right because..." "This one is wrong about..."
In this way, not only do they still learn the actual material, they also get some insight into evaluating sources on their own. And you learn where all the cheat sources are without having to look yourself. Win-win? :)
Note: I have no education background whatsoever except as a student.