I called this a webquest, but I don't direct them to specific websites for the information so I'm not sure it technically qualifies as one. However, this handout is a great way to summarize all the important information about El Nino, La Nina, and the normal situation (some call it 'la nada'), and unfolds as a guided inquiry type of assignment. You can do it with your students as a class, or you can give it to them to noodle through. I couldn't find anything that was a concise lesson for El Nino, so I created one. I will upload an answer key soon.