Here is an easy, but fun vertical step combo that I used last night.  It is simple to follow and teach, but criss-crossing the step gets the heartrate up nicely.

Combo:

Note: Start on the left side of the step, towards the back.

4 - Over the Top, R Lead

4 - Diagonal Over the Top, L Lead.  Move to the front of the step.

4 - Over the Top, R Lead.  Stay at the front of the step.

4 - One knee:  Use it to back up again.  I usually cue it as “One hop back”

6 - Two-knee Repeater

2 - Two bounces in place, like jumping rope

4 - Rocking Horse: One hamstring curl (2) One knee (2)

4 - One Jumpshot

Reverse.

 I usually teach this one by doing three of everything, then shortening it up; therefore, no fancy layering techniques.  :) 

Have fun!