Here's another great warm-up activity from Ross Chakrian. Ross created this in Powerpoint and I have converted it to video format to make it playable on any device here: goo.gl/JMCt3Z. (30 seconds locomotor, 10 seconds dice roll, 25 seconds choice activity).
We have, also, added a second version here: goo.gl/jyC6xA (30 seconds locomotor (JOG instead of WALK), 10 seconds dice roll, 40 seconds choice activity).
I just LOVE the student choice aspect of this warmup.
In case you don't have enough dice for the number of groups you want to have: If you have devices, you can have students have their devices around the edges of the gym and they can use this online virtual dice roller: http://www.curriculumbits.com/prodimages/details/maths/doubledice.html