The seven children in this video clip are drawing their designs for how to house various types of house pets. Notice the strategies that Myra and Jenson use to differentiate two building materials – wood and chicken wire. Both girls represent the opaque character of the wood by filling it in with black marker. In contrast, Myra draws a series of open shapes to symbolize the vacant spaces of the chicken wire, and Jenson draws a series of vertical lines with vacant spaces in between. Later, Seth uses a single line to indicate that the bottom floor is divided into two spaces. As they draw, the children demonstrate flexibility in their symbol use by modifying their representations to include additional features suggested by the teacher (i.e., doors). Although the children talk about housing guinea pigs, kittens, puppies, hamsters, and fish, their drawings represent general knowledge about the structure of a house for pets.