Mandy, tell your teens that what happened in the OT is/was fulfilled in the NT. Then lead them in how Jesus and the OT connect. This will help them whenever they read the OT, they will look at how Jesus is talked about or revealed. Don't expect them to tell you big revelations when you have not told them either. Remember they learn as you teach them not as you expect them. Step by step, that's how we learn, it's a process.
Hope that helps...........