In this clip the students are unsure whether the length and width of the box co-vary so she has them discuss other the relationships between quantites to help them.
In this clip the teacher leads a discussion about whether or not there are two boxes that can have the same volume.
Box Problem Summary, Clip 3, 5:02
In this case the teacher initially asks them about co-varying the length and the width of the box to which the students respond they do not. She then makes the move to have the discuss co-variation between the length of the cutout and the volume. This is something they encountered in a previous class so she is looking to build on some of their prior knowledge to get them to think about the original question.
The teacher also incorporates the Explore Box applet in order to help the students reason about the original question. If the students are struggling, this may be a necessary move.
