I want my students to take photos and send them via email
direct to a slideshow embedded to my class page.
Step 1: Open https://picasaweb.google.com/lh/settings
When the Picasa Web Albums setting page opens, click
"Allow me to upload photos by email"
Step 2: Enter the secret word. That will generate a unique email address.
Step 3: Send a photo to that address then find the photo in your
Web Albums and get the embed code for the slide show Picasa creates.
Step 4: Grab the embed code and add it to your Google Site.
People send to email address and the photo just becomes a part of the Slide Show embedded on your Google Site.