Science Buddies: "Ask an Expert"

Please help! I can't figure out my controlled variables.
My project is Emotional Resonance in Black and White and Colour photos. I tested 2 students at a time, in the same room, all between the ages of grade 7 and 8. The sat in a quiet room, backs to each other, and looked at 2 sets of 22 photos, 11 colour and 11 in black and white. Student 1 looked at #'s 1-11 B&W, 12-22 colour, and the opposite for student 2. They then wrote down what emotion each photo made them feel, and ranked the intensity of it on a scale of 1-10. What are my independed, dependent, and controlled variables?

Thanks so much!

It sounds like your independent variable (what you're changing) is whether the picture is b&w or colored. The dependent variable (what you're measuring in the experiment/what is affected) is the emotional level the two different sets of picture. The controlled variables (what stays the same in the experiment) could be the same pictures used for each student, same grade range, same location, etc.