Story and songs for subjunctive: indefinite/negative antecedent

Subjunctive by reason of indefinite or negative antecedent... doesn't that sound fun? This is my story for this reason of subjunctive. We do this in the spring semester of Spanish 2.
Our principal wakes up in the morning and goes to school. He asks the woman at the front desk, "I'm looking for the student who... (fill in talents of students in your class)" Ex: "Busco al estudiante que toca la guitarra mejor que Santana." (This is diagrammed/drawn on the left of the board.)
The woman at the front desk doesn't know (name). She calls the teacher over the intercom and says, "Do you have a student who... (toque la guitarra mejor que Santana)." (This is diagrammed/drawn in the middle.)
The teacher in the classroom has no clue who (name) is. She says, "There's no student here who (toque la guitarra mejor que Santana)."
We go through the sequence for at least 3, preferably four talents. By the third, maybe by the second, students should be making the subjunctive switch for you, especially if you write the final vowels in the verbs in a different color, even though they don't know why.
At the end of the story, it turns out that the reason none of the students were at the school was that (principal) was at (rival school), and actually it was all a dream!
After the story, I draw a head with a check mark on the left, a head with a question mark in the middle, a head with an X on the right. Students fairly readily grasp, "En su mente, sí existe." "En su mente, ¿existe esa persona? No sabe." "En su mente, la persona no existe."

The two songs that go along with this are La Traviesa by Juan Luis Guerra, and Esto es lo que soy by Jesse y Joy.

Remember to ask, ask, ask. If you present them with the input the right way, they'll figure it out themselves, but you can't assume they know it until they tell you so.

Most of all, have fun and make it fun. Fun = motivating.