As a science teacher at a junior high school in Oregon, I am always looking for ways to make the subject matter interesting to my students.

One day, while planning a lesson on puberty and the human reproductive system, I realized that I had the opportunity to do just that.

My daughter, who had just turned 13, was showing all the signs of puberty, including small breasts and a light coat of pubic hair.

I realized that she would make a wonderful live model for my four class sessions.

When I told her about it, she was understandably hesitant about being naked in front of large groups of kids her age.

But I managed to convince her because I don't teach at the school she attends, and she knows none of the students there.

And so on the day of the class, Casey sat in the storage room of my classroom, wearing only a bathrobe.

Once the first class had settled down, with their chairs in a circle, I called her out, and told her to stand in the middle.

She was clearly nervous and trembling, but it was clear that she would do what I said.

"Ok, hand me your robe, please," I said.

She slowly took off the robe, and stood naked in front of the class of 12 boys and 14 girls.

Immediately her nipples hardened, and I took the opportunity for a "teachable moment," talking about contractile tissue, and its role in keeping vital parts of the body warm.

I also talked about how most female breasts are not evenly shaped, and told them to take a close look at Casey's, and the fact that her left breast is slightly larger than the right.

I then asked the kids if they wanted to feel her breasts. Few of the girls did, but predictably all the boys raised their hands.

I didn't tell Casey I was going to let my students touch her, and I actually didn't either until she was standing there looking forlorn.

"Daddy...," she whispered, imploring me with her eyes to change my mind. I ignored it.

And so one by one, the boys cupped her breasts, and gently stroked her nipples before returning to their chairs. Casey just stood there, her eyes on the ground and her face bright red with embarrassment. I then told her to get on the table I had set up with cushions from the teachers' lounge.

She lay on her back, and I instructed to put her legs over two blanket-draped chairs on either side of the desk, the effect of which was like the stirrups in a gynecologist's office.

There, with her legs spread wide open before a class of 26 kids, she looked absolutely mortified. I positioned a camera toward her vagina, and proceeded to explain the various parts, including the inner and outer labia, urethra and the clitoris. Then, I again let the kids line up and, after washing their hands, let them get a sense of what a vagina feels like.

The entire time, I saw Casey trying to stifle tears in her eyes, which she kept closed.

Finally, it was time for a quiz, for which each student had to come to where Casey was lying, and pointing out at least four of the anatomical parts we had discussed.

After the bell rang and the kids left, Casey hopped off the table and put her bathrobe on.

"Just four more classes," I told her.