In this card sort activity, students work with a partner to determine the slope of twelve different lines. There is one line per card, and each line is described by its graph on a coordinate plane or by two points on the line. After determining slopes, partners sort their cards based on whether the lines are parallel, perpendicular, or neither. They record their results on a template.
There are three sets of cards, each one at the same level of complexity. This provides a wider variety of problems and allows the teacher some flexibility in assigning cards to partners.