Not only teens, but for elementary age children as well. Some children and teens (adults too!) with autism may not always have a clear cognitive understanding on 'yes' and 'no'.
For example, my son is 9 and he is now becoming increasingly aware of his decision making. His 'yes' and 'no' are more concrete and decisive. Sometimes he would say "yes" to things he didn't want to do or because it seemed like the "right answer."
With consistency, having open and honest discussions, and setting up scenarios, your child can and will learn how to navigate in this beautiful (and unstable!) world.
As always, if you need additional information/resources on transitioning your child or teenager- dont hesitate to contact me Anastasia Ford(Disability Advocacy Coordinator) at email@example.com. Some of you may have firstname.lastname@example.org and that is ok too.