Since he was the idea behind this children's toy, you may want to incorporate a picture book story about a teddy bear, talk about the history of the teddy bear and/or bring in teddy bears. I personally like the story related to the song
"The Teddy Bear Picnic." You can get a copy of the book (along with the song sung by Bing Crosby) by Jimmy Kennedy at half.com.
(I haven't taught first grade in many years, so it's possible that our first graders today would find this activity "babyish" but I thought it would be fun and get all the kids connected to a man who lived so long ago...)