Above all be patient, I remember learning. I had two instructors. One was very calm and patient, the other was very high strung and stressful to learn from. I learned most everything from the calm patient one. You say each student has had a couple flights. for some students this is just the beginning. Everybody learns at their own pace, not yours. When you agree to teach somebody, you make a big commitment, but ultimately, the student decides the pace at which he learns.