Overview:  In this launch the teacher shows students a picture of a drawing in 2-point perspective as a way to introduce the idea of perspective drawing.  Before showing students anything, the teacher asks students if any of them knows what perspective drawing is.  Two students offer ideas, that there is a point everything collapses to, and it allows the viewer to see which objects are farther away.  The teacher passes around copies of the painting “Paris Street: Rainy Day”, which is a painting in 2-point perspective.  Students view the picture and notice that some objects are farther away than others.  One students points out the horizon line.  The teacher continues asking students what they notice about the painting until Aditi says that the painting vanishes on both sides, indicating the two vanishing points.  The teacher uses this opportunity to show students that the painting has two vanishing points.  Then, the teacher tells students that they will work on a problem that requires them to do some perspective drawing.  The teacher tells students they will use properties of perspective to make observations and add items to the drawing.

Prior knowledge:  With this launch the teacher elicits students’ prior knowledge of the context of perspective drawing.  In contrast to Launch 1, in which the teacher shows students pictures with very complicated perspectives, the teacher in this launch uses a painting for which the 2-point perspective is very obvious as an opportunity to see what students observe in the picture.  Students make observations that are characteristic of perspective drawing, such as the fact that certain objects look farther away, there is a horizon line, and there are two vanishing points.  The teacher implies to students that they will need to use their knowledge of the context of perspective drawing to work on the problem.

Other points of interest:  When the teacher asks students what they know about perspective drawing, and then when she asks students to make observations about the painting, the teacher asks questions to which she does not know how students will answer.  This practice is a departure from more typical IRE (Mehan, 1979) interactions in classrooms, when a teacher generally asks questions to which he or she already knows the appropriate response.  By asking students what they notice, the teacher does not know in advance what responses students will offer.  This pattern of questioning allows students some agency in determining the direction of the discussion (González & DeJarnette, 2012).  At the same time, the teacher seems to have a specific point she wants to make, specifically that the picture contains two vanishing points.  Because of this, the teacher allows students to offer their ideas until a student brings up the idea of the vanishing point.  Once the vanishing point becomes a topic of discussion, the teacher stops inviting students to make observations about the painting.