Give her a hand

You look around, none of the students are paying any attention and the teacher is focused on her lesson. You take a chance and put a hand on Elizabeth's knee.

She jumps a little, and looks at you, shocked. "What are you doing?", she mouths. You point at her phone, and mouth, "need a hand?" She stares at you a moment, then moves her desk closer as quietly as possible.

You move your hand over her thigh and up her skirt as she leans back in her desk, still looking at her phone. She must really enjoy whatever she's looking at, because her panties are soaked. The angle is a bit odd, but you manage to pull them aside and slip a finger in.

You watch her chest move as you finger her, slowly at first and then faster. You can hear her breath but you seem to be the only one. You slip another finger in. She's no longer looking at her phone, she's now holding against her chest, her eyes closed.

You're both having a great time, but then the bell rings. You pull your fingers out and wipe them on another students back as you prepare to leave.