Great activity for building lower body strength. It is also good for using as fitness warm-ups at any age level. The task can be modified at the higher levels to challenge the students as well. The following concepts and skills are covered in this activity: muscular strength, muscular endurance, cardiovascular endurance, speed, quickness, agility, and gross motor skills. This activity can also be used with putting students on top of the mats or making objects heavier or lighter. The equipment can be modified as well to make it easier on the smaller kids.