This article describes the light-based science circus the authors developed and tested with a fifth-grade class at Blackwell Elementary School in Richmond, Virginia. A science circus is a set of activities done in any order that together illustrate complementary properties of a science topic. As in a traditional circus, several "performances" occur at the same time, and students focus their attention on one activity while others are going on simultaneously. Similar to the ringmaster of a circus, the teacher guides and directs students as they circulate through the stations. Many science topics are complex, and two or three activities are often insufficient to support student concept development. How can teachers fit more activities on a topic into the classroom schedule? The authors' answer was to alter the pattern of doing science activities in sequence and instead do several at the same time. With the time saved they had more time to lead discussions with the entire class, helping construct understandings about the topic. There are three steps to a science circus on any topic: (1) the hook, a question that generates student interest in the topic; (2) the activities that explore that question and other aspects of the topic; and (3) the forum, the teacher-led class discussion of the topic. For this study of light, the hook was a thought-provoking question related to a misconception many children and adults have about being able to see an object even though there is no light shining on the object: "If you were in a completely dark room, would you be able to see anything?" The students were divided over the answer. Several insisted you could see in complete darkness, while others argued you had to have some light. The authors led them to the second step of the circus by explaining they were going to do some activities that might show them the answer to that question. The science circus activities are described in Figure 1.