This topic concerns resistive forces against motion. It begins by considering drag forces in general before shifting the focus to air resistance. There is much opportunity for student investigation in this area and you may choose to extend one of the exercises for that purpose. You will also need to consider the depth of treatment you want to give the subject – whether or not your students will respond to a quantitative approach or if a qualitative appreciation of the ideas is sufficient. Here, we have chosen to emphasize the qualitative understanding of the effects of forces.