I Love My Students

"I want to talk about my favorite book. My favorite book is "Traveling Pants." It is the story of the Pants. It is very exciting and interesting. Thank you." - one of my more talented students (check out the complete sentences and proper punctuation.)

What are the Pants? Where do they go? I wonder if I can find this book in English...

Also, I think "pants" in Japanese means underwear. I am not sure how that fits into this, if it does at all.