It can be tricky to make students more active in some of the more abstract and “mathy” topics in our curricula. Many teachers default to lecture in those situations. Carefully structuring a lesson so that students are given an opportunity to explore, converse, discover patterns, and invent rules can be a great way to activate students as owners of their learning.
Sam Shah has posted a nice introduction to rational functions that does everything described above. His blog post includes handouts you can use with your class.