This activity (on page 2 of the PDF under SciGirls Activity: Luge) is a full inquiry-based challenge related to motion and design optimization. Groups of learners will use construction paper to build a model bobsled run for a marble to follow down a ramp. They are then challenged to get the marble down the ramp in a time of 12 seconds, continuing to modify and re-test their run until they reach this goal. Learners can track their progress by creating a bar chart that shows the speed of each design version. This is a great activity for developing team-building skills. Relates to linked video, DragonflyTV GPS: Luge.