Class Warm Ups Running in the Jungle (Kids)
Line the kids up get them jogging on the spot, then present them with a set of challenges often found in the jungle. Lions, Snakes, Low branches, High branches, Swamps, Rivers, Vines, Hunters, Sinking sand.... Have a preplanned method for dealing with each challenge and lead your kids in it. If they stop... the jungle eats them (A senpai) and draggs them off to do a normal jogging and streching warm up without the fun.
Lion -- Roar at it and lean forwards streching your arms out like a big mouth.
Snake -- Strech your arms up and wave them side to side, while pressed together to imitate a snake.
Low branches -- Drop into push up position and roll under the branch, crocodile roll style
High branches -- Jump and touch your ankles with your hands
Swamps -- Swim on your back **swing your arms backwards**
Hunters -- Run on the spot as fast as you can to out pace the hunters
Sinking sand --
Rivers -- Swim on your front **swing your arms forewards**
Vines -- Dodge the vines by dropping into alternate side stances
Sinking Sand -- Lie down really really still and then edge yourself using your toes untill you are free.
OTHERS -- anything you can think of.
Kata Warm Up ((Anyone))
Have the class perform a common kata they all know well, but have them perform it slowly and gently, with "softened" stances, allowing them to move through each movement at half speed with little force...
Perform the same kata again, but this time at 75% stance and technique, include correct breathing.
Perform the same kata a third time at 100% stance and technique, adding in deep breathing and shouts to extra places.
Technique Warm Up ((Anyone))
Similar to the kata warm up, choose a series of techniques, and stances, from Keri (kicks) Tsuki (Punches) and Dachi (Stances) lead the group or yourself through this selection at half speed and force without streching, again at greater speed and force and again at greater speed and force.
This follows the idea that performing something slowly allows you to warm up your muscles, getting blood flowing and encouraging temporary flexibility.
Sparring Warm up ((Anyone))
Following the same idea of the above, you enter into a light contact slow movement "Soft kumite" sparring at about 70% speed and 30% applied force, moving slowly and softly in a none competative manner, the two fighters pushing each other to use more and more challanging techniques, slowly and gently to warm up muscles and joints in the use of the techniques.
Shadow ((Kids))
Turn your back on the kids, and have a senpai act as a "Light" now all the kids have to follow your movements while staying the other side of you than the "Light" if the "light" gets too far past you without one or more of the kids circling you to keep behind you then their shadow gets destroyed.

This means you can lead them through anything from jogging to situps and they think it is a game.
Solo Warm Ups Kata Warm Up, ---- See Above
Technique Warm up, ---- See Above
Basic Warm Up
Jogging on the spot, Spotty Dogs, Arm swings, Hopping, Jumping, Leg lifts, Spinning, Twisting, Rolling.
thats a starter from me.