Welcome to the environment and nature part of the site. These are nice topics to include in your ESL lessons whether you use them as discussion topics or as themes for worksheets. With 297 worksheets to choose from, there is bound to be something your students will enjoy. This worksheet is great for practicing numbers and certain animals. The description for the worksheet even mentions that you will need to introduce the word endangered to students and that for an extra activity, you can practice using There is and There are. This activity was created for beginners but there are worksheets for students of every level. There are a lot of word searches available as well as projects and some discussion topics.
This is a great discussion topic, especially with intermediate and advanced students, because there are many related tangents you can choose from such as recycling and global warming. These are very important, modern issues that people should be more aware of. Of course these are also appropriate topics for young learners who are curious about the world around them. The material for these lessons would obviously be more basic but you could still introduce topics like recycling since they are probably already aware of its importance.