<iframe src="https://player.vimeo.com/video/277195853?background=1" width="640" height="360" frameborder="0" allowfullscreen></iframe>
Beginning (gram on the left) – Standing with your feet together, step one leg back to a lunge then back together. Keep repeating while alternating legs.
Intermediate (mom in the middle) – Starting with your feet together, jump out to a lunge, then back to standing with your feet together. Keep repeating while alternating legs.
Advanced (me on the right) – Continuous hopping/jumping lunges, keep repeating and alternating legs.