Conflict with a Class

I'm having trouble with one of my classes.  I appreciate them sitting quietly when Ms. Tufano or myself is speaking, but when it comes to time participate, ask questions, or check for understanding, all we get our blank faces without even a nod.  I have not resolved this conflict.  I feel like the students are not enjoying the lessons.  That makes me sad.  

                                                                                                                                      Ms. Crawford :(