Each month's winner, drawn randomly from the pool of correct entries, receives a pre-determined prize such as an "I [heart] Science" T-shirt or a AAAS Digital Membership. The first winner, Laura McShane, is the Children's Librarian at the Cleveland Public Library. Contestants must be over 18 to enter, but teachers may submit a guess on behalf of their class.
Thurston anticipates that classroom guesses will pick up as the school year gets underway. "Teachers can guide students to identify what observations can be made from the image and to determine clues or characteristics that will help students make an educated guess," she said.
"While the contest is live, very little information about the image is provided. However, once the contest is over we provide a thoughtful description about the image and point teachers to related Science NetLinks resources. All finished contests  are archived so teachers can conduct their own contests at any point, not just when the contest is open."
Thurston and her colleagues hope to learn how teachers are using the Mystery Image Contest in their classrooms. To encourage feedback they have started a discussion in their All About Science  online group, where teachers can share ideas and suggestions.
Launched in 1997, Science NetLinks was revamped in 2011 to provide new options for exploring its hundreds of lesson plans, online tools, special resource collections and after-school activities for K-12 teachers, students and families. Science NetLinks also features two AAAS news feeds: Science for Kids , which offers student-friendly stories based on reports from the journal Science, and ScienceNOW , the journal's daily online news section.
Content from Science NetLinks is also featured on the Verizon Foundation's Thinkfinity.org  site, which provides free, Internet-based educational resources and an online community for educators. Science NetLinks receives more than 280,000 visits each month.
Submit your best guess ! Science NetLinks mystery image for September [U.S. Geological Survey]