It involves a 3 step process. Be cautious not to skip the SEE step and go directly to the think. In this first step it insures students look closely at the image which gives the foundation for steps Think and Wonder.
1. Teacher chooses the image.
2. See: Ask students what they notice?
3. Think: What are they thinking from their observations?
4. Wonder: What questions do they have now?
5. Share their thinking. Perhaps unanswered questions can be written down and posted for future discussions.
If you want a more in-depth explanation of this strategy see Making Thinking Visible by Ritchart, Church, and Morrison